Metrics _msearch Timeouts

[kobelb]

ES master is throwing a 400 Bad Request when the timeout is specified in the _msearch header, and this should be moved to the body and units should be specified.

Doing a quick search, I found the following usages:

• src/core_plugins/metrics/server/lib/vis_data/table/get_request_params.js
• src/core_plugins/metrics/server/lib/vis_data/series/get_request_params.js
• src/core_plugins/metrics/server/lib/vis_data/get_annotations.js

[elasticmachine]

Pinging @elastic/kibana-app