KAFKA-5119: Ensure global metrics are empty before running testMetricCollectionAfterShutdown

[ijuma]

Depending on the test execution order, the global registry would
contain some metrics causing the test to fail.

[ijuma]

We were able to trigger this problem by running the test suite in a particular slave of Confluent Jenkins:

https://jenkins.confluent.io/job/kafka-branch-builder/112/

Running the test suite with the fix:

https://jenkins.confluent.io/job/kafka-branch-builder/115/

[ewencp]

@ijuma LGTM once we have the jenkins builds passing, thanks for tracking this down. And I assume the latest passing build on Confluent's jenkins is also verifying the fix no longer triggers the issue there.

[ijuma]

@ewencp, that's right, the test passed in two Confluent Jenkins builds for the whole test suite.

[asfbot]

Refer to this link for build results (access rights to CI server needed):
https://builds.apache.org/job/kafka-pr-jdk8-scala2.11/3180/
Test PASSed (JDK 8 and Scala 2.11).

[asfbot]

Refer to this link for build results (access rights to CI server needed):
https://builds.apache.org/job/kafka-pr-jdk8-scala2.11/3189/
Test PASSed (JDK 8 and Scala 2.11).

[asfbot]

Refer to this link for build results (access rights to CI server needed):
https://builds.apache.org/job/kafka-pr-jdk7-scala2.10/3174/
Test PASSed (JDK 7 and Scala 2.10).

[asfbot]

Refer to this link for build results (access rights to CI server needed):
https://builds.apache.org/job/kafka-pr-jdk8-scala2.12/3175/
Test PASSed (JDK 8 and Scala 2.12).

[asfbot]

Refer to this link for build results (access rights to CI server needed):
https://builds.apache.org/job/kafka-pr-jdk7-scala2.10/3185/
Test PASSed (JDK 7 and Scala 2.10).

[asfbot]

Refer to this link for build results (access rights to CI server needed):
https://builds.apache.org/job/kafka-pr-jdk8-scala2.12/3184/
Test PASSed (JDK 8 and Scala 2.12).