[DataDog/dd-agent][kafka] Update incorrect kafka.yaml.example bean names

[stb2132]

What does this PR do?

This PR updates four of the bean names listed in the kafka.yaml.example file to accurately reflect changes that have been made to Kafka.

Updated:

kafka.server:type=ProducerRequestPurgatory,name=PurgatorySize
kafka.server:type=FetchRequestPurgatory,name=PurgatorySize
kafka.controller:type=ControllerStats,name=LeaderElectionRateAndTimeMs
kafka.controller:type=ControllerStats,name=UncleanLeaderElectionsPerSec

To:

kafka.server:delayedOperation=Produce,name=PurgatorySize,type=DelayedOperationPurgatory
kafka.server:delayedOperation=Fetch,name=PurgatorySize,type=DelayedOperationPurgatory
kafka.controller:name=LeaderElectionRateAndTimeMs,type=ControllerStats
kafka.controller:name=UncleanLeaderElectionsPerSec,type=ControllerStat

Motivation

A more accurate example file, and requests: https://trello.com/c/V80dk24K/2051-update-kafka-yaml-default-bean-names

Additional Notes

Please see the reference here:
https://issues.apache.org/jira/browse/KAFKA-3480

[stb2132]

Hey, I was unsure of what was necessary for testing with this, so I submitted in order to get the ball rolling. Please let me know if anything additional is needed.

[estib]

thanks for getting this started! do we know if these updates are appropriate across all versions of kafka? or if only some of them? that may be hard to find out if I remember correctly, since kafka's own docs seemed to have outdated bean names last time i checked.

[alcy]

This will be useful for our organization. I can confirm this is required for version 0.9.0.1 at least. @stephenlechner thanks for pointing out the PR.

[jeffwidman]

What's needed to get this reviewed/merged?

[jeffwidman]

@stb2132 Can you migrate this to be a PR against https://github.com/DataDog/integrations-core/blob/master/kafka/conf.yaml.example ?