Skip flaky Monitoring Shard Allocation Per Node tests

[tylersmalley]

Seeing this failure across multiple PR's off of master.

https://kibana-ci.elastic.co/job/elastic-kibana-pull-request/5365/
https://kibana-ci.elastic.co/job/elastic-kibana-pull-request/5336/

Confirmed with @elastic/kibana-management to disable in the meantime. Will create a follow-up issue to revive the test after it has been disabled.

22:15:50            │ proc  [ftr]        └- ✖ fail: "Monitoring app Elasticsearch shard legends Shard Allocation Per Node "before all" hook"
22:15:50            │ proc  [ftr]        │        tryForTime timeout: Error: tryForTime timeout: [POST http://localhost:9515/session/69029da72a784e31721e74b2f4a5dc2c/element / {"using":"css selector","value":"[data-test-subj~=\"elasticsearchNodesListingPage\"]"}] no such element: Unable to locate element: {"method":"css selector","selector":"[data-test-subj~="elasticsearchNodesListingPage"]"}
22:15:50            │ proc  [ftr]        │         (Session info: chrome=65.0.3325.162)
22:15:50            │ proc  [ftr]        │         (Driver info: chromedriver=2.36.540471 (9c759b81a907e70363c6312294d30b6ccccc2752),platform=Linux 4.9.0-5-amd64 x86_64)
22:15:50            │ proc  [ftr]        │           at Server._post (/var/lib/jenkins/workspace/elastic+kibana+pull-request+multijob-x-pack/kibana/test/functional/services/remote/verbose_remote_logging.js:34:21)
22:15:50            │ proc  [ftr]        │           at runRequest (/var/lib/jenkins/workspace/elastic+kibana+pull-request+multijob-x-pack/kibana/node_modules/leadfoot/Session.js:92:40)
22:15:50            │ proc  [ftr]        │           at /var/lib/jenkins/workspace/elastic+kibana+pull-request+multijob-x-pack/kibana/node_modules/leadfoot/Session.js:113:39
22:15:50            │ proc  [ftr]        │           at new Promise (/var/lib/jenkins/workspace/elastic+kibana+pull-request+multijob-x-pack/kibana/node_modules/dojo/_debug/Promise.ts:411:4)
22:15:50            │ proc  [ftr]        │           at Session._post (/var/lib/jenkins/workspace/elastic+kibana+pull-request+multijob-x-pack/kibana/node_modules/leadfoot/Session.js:67:10)
22:15:50            │ proc  [ftr]        │           at Session.find (/var/lib/jenkins/workspace/elastic+kibana+pull-request+multijob-x-pack/kibana/node_modules/leadfoot/Session.js:1328:15)
22:15:50            │ proc  [ftr]        │           at Command.<anonymous> (/var/lib/jenkins/workspace/elastic+kibana+pull-request+multijob-x-pack/kibana/node_modules/leadfoot/Command.js:42:36)
22:15:50            │ proc  [ftr]        │           at /var/lib/jenkins/workspace/elastic+kibana+pull-request+multijob-x-pack/kibana/node_modules/dojo/_debug/Promise.ts:393:16
22:15:50            │ proc  [ftr]        │           at run (/var/lib/jenkins/workspace/elastic+kibana+pull-request+multijob-x-pack/kibana/node_modules/dojo/_debug/Promise.ts:237:8)
22:15:50            │ proc  [ftr]        │           at /var/lib/jenkins/workspace/elastic+kibana+pull-request+multijob-x-pack/kibana/node_modules/dojo/_debug/nextTick.ts:44:4
22:15:50            │ proc  [ftr]        │           at _combinedTickCallback (internal/process/next_tick.js:131:7)
22:15:50            │ proc  [ftr]        │           at process._tickCallback (internal/process/next_tick.js:180:9)
22:15:50            │ proc  [ftr]        │           at Command.find (/var/lib/jenkins/workspace/elastic+kibana+pull-request+multijob-x-pack/kibana/node_modules/leadfoot/Command.js:23:10)
22:15:50            │ proc  [ftr]        │           at Command.prototype.(anonymous function) [as findByCssSelector] (/var/lib/jenkins/workspace/elastic+kibana+pull-request+multijob-x-pack/kibana/node_modules/leadfoot/lib/strategies.js:29:16)
22:15:50            │ proc  [ftr]        │           at _ensureElementWithTimeout (/var/lib/jenkins/workspace/elastic+kibana+pull-request+multijob-x-pack/kibana/test/functional/services/find.js:71:29)
22:15:50            │ proc  [ftr]        │           at retry.try (/var/lib/jenkins/workspace/elastic+kibana+pull-request+multijob-x-pack/kibana/test/functional/services/find.js:51:33)
22:15:50            │ proc  [ftr]        │           at tryCatcher (/var/lib/jenkins/workspace/elastic+kibana+pull-request+multijob-x-pack/kibana/node_modules/bluebird/js/main/util.js:26:23)
22:15:50            │ proc  [ftr]        │           at Function.Promise.attempt.Promise.try (/var/lib/jenkins/workspace/elastic+kibana+pull-request+multijob-x-pack/kibana/node_modules/bluebird/js/main/method.js:31:24)
22:15:50            │ proc  [ftr]        │           at attempt (/var/lib/jenkins/workspace/elastic+kibana+pull-request+multijob-x-pack/kibana/test/common/services/retry.js:41:16)
22:15:50            │ proc  [ftr]        │           at tryCatcher (/var/lib/jenkins/workspace/elastic+kibana+pull-request+multijob-x-pack/kibana/node_modules/bluebird/js/main/util.js:26:23)
22:15:50            │ proc  [ftr]        │           at Promise._settlePromiseFromHandler (/var/lib/jenkins/workspace/elastic+kibana+pull-request+multijob-x-pack/kibana/node_modules/bluebird/js/main/promise.js:503:31)
22:15:50            │ proc  [ftr]        │           at Promise._settlePromiseAt (/var/lib/jenkins/workspace/elastic+kibana+pull-request+multijob-x-pack/kibana/node_modules/bluebird/js/main/promise.js:577:18)
22:15:50            │ proc  [ftr]        │           at Promise._settlePromises (/var/lib/jenkins/workspace/elastic+kibana+pull-request+multijob-x-pack/kibana/node_modules/bluebird/js/main/promise.js:693:14)
22:15:50            │ proc  [ftr]        │           at Async._drainQueue (/var/lib/jenkins/workspace/elastic+kibana+pull-request+multijob-x-pack/kibana/node_modules/bluebird/js/main/async.js:123:16)
22:15:50            │ proc  [ftr]        │           at Async._drainQueues (/var/lib/jenkins/workspace/elastic+kibana+pull-request+multijob-x-pack/kibana/node_modules/bluebird/js/main/async.js:133:10)
22:15:50            │ proc  [ftr]        │           at Immediate.Async.drainQueues [as _onImmediate] (/var/lib/jenkins/workspace/elastic+kibana+pull-request+multijob-x-pack/kibana/node_modules/bluebird/js/main/async.js:15:14)
22:15:50            │ proc  [ftr]        │           at runCallback (timers.js:810:20)
22:15:50            │ proc  [ftr]        │           at tryOnImmediate (timers.js:768:5)
22:15:50            │ proc  [ftr]        │           at processImmediate [as _immediateCallback] (timers.js:745:5)
22:15:50            │ proc  [ftr]        │           at attempt (/var/lib/jenkins/workspace/elastic+kibana+pull-request+multijob-x-pack/kibana/test/common/services/retry.js:38:17)
22:15:50            │ proc  [ftr]        │           at tryCatcher (/var/lib/jenkins/workspace/elastic+kibana+pull-request+multijob-x-pack/kibana/node_modules/bluebird/js/main/util.js:26:23)
22:15:50            │ proc  [ftr]        │           at Promise._settlePromiseFromHandler (/var/lib/jenkins/workspace/elastic+kibana+pull-request+multijob-x-pack/kibana/node_modules/bluebird/js/main/promise.js:503:31)
22:15:50            │ proc  [ftr]        │           at Promise._settlePromiseAt (/var/lib/jenkins/workspace/elastic+kibana+pull-request+multijob-x-pack/kibana/node_modules/bluebird/js/main/promise.js:577:18)
22:15:50            │ proc  [ftr]        │           at Promise._settlePromises (/var/lib/jenkins/workspace/elastic+kibana+pull-request+multijob-x-pack/kibana/node_modules/bluebird/js/main/promise.js:693:14)
22:15:50            │ proc  [ftr]        │           at Async._drainQueue (/var/lib/jenkins/workspace/elastic+kibana+pull-request+multijob-x-pack/kibana/node_modules/bluebird/js/main/async.js:123:16)
22:15:50            │ proc  [ftr]        │           at Async._drainQueues (/var/lib/jenkins/workspace/elastic+kibana+pull-request+multijob-x-pack/kibana/node_modules/bluebird/js/main/async.js:133:10)
22:15:50            │ proc  [ftr]        │           at Immediate.Async.drainQueues (/var/lib/jenkins/workspace/elastic+kibana+pull-request+multijob-x-pack/kibana/node_modules/bluebird/js/main/async.js:15:14)
22:15:50            │ proc  [ftr]        │           at runCallback (timers.js:810:20)
22:15:50            │ proc  [ftr]        │           at tryOnImmediate (timers.js:768:5)
22:15:50            │ proc  [ftr]        │           at processImmediate [as _immediateCallback] (timers.js:745:5)

Failure Screenshot:

[elasticmachine]

💚 Build Succeeded

• continuous-integration/kibana-ci/pull-request

[tylersmalley]

@elastic/kibana-monitoring

[tsullivan]

LGTM

[tylersmalley]

Created a follow-up issue here: #20772