[SPARK-15783][CORE] still some flakiness in these blacklist tests so ignore for now

[squito]

What changes were proposed in this pull request?

There is still some flakiness in BlacklistIntegrationSuite, so turning it off for the moment to avoid breaking more builds -- will turn it back with more fixes.

How was this patch tested?

jenkins.

[SparkQA]

Test build #60055 has finished for PR 13528 at commit a3c75da.

• This patch fails Spark unit tests.
• This patch merges cleanly.
• This patch adds no public classes.

[squito]

merged to master.

not closing the jira for now since I hope to actually fix the tests, not just turn them off

[squito]

forgot to add -- I did look at the test failures, they are unrelated flakiness

[sameeragarwal]

@squito the last master build failed a number of tests on this commit: https://spark-tests.appspot.com/builds/spark-master-test-maven-hadoop-2.2/1206. Could those failures be related?

[sameeragarwal]

(most likely not; https://spark-tests.appspot.com/tests/org.apache.spark.deploy.LogUrlsStandaloneSuite/verify%20that%20log%20urls%20reflect%20SPARK_PUBLIC_DNS%20%28SPARK-6175%29 seems to be the culprit so I'll just re-kick the build)

[squito]

thanks @sameeragarwal , I took a look and reached more or less the same conclusion. I don't understand why a failure in LogUrlsStandaloneSuite isn't getting properly cleaned up -- all the right hooks for LocalSparkContext seem to be there -- but it certainly looks like the problem is related to that somehow, but maybe there is something there if anybody wants to track down the flakiness.

then again, I've been wrong about this test multiple times now, so please lemme know if there are continued issues.