KAFKA-13234; Transaction system test should clear URPs after broker restarts

[hachikuji]

Clearing under-replicated-partitions helps ensure that partitions do not become unavailable longer than necessary as brokers are rolled. This prevents flakiness due to transaction timeouts.

Committer Checklist (excluded from commit message)

• Verify design and implementation
• Verify test coverage and CI build status
• Verify documentation (including upgrade notes)

[hachikuji]

Successful test run for transactions_test.py: http://confluent-kafka-branch-builder-system-test-results.s3-us-west-2.amazonaws.com/2021-08-26--001.system-test-kafka-branch-builder--1630005021--hachikuji--KAFKA-13234--e05a85bca5/report.html

[hachikuji]

Successful test run for group_transactions_test.py: http://confluent-kafka-branch-builder-system-test-results.s3-us-west-2.amazonaws.com/2021-08-26--001.system-test-kafka-branch-builder--1630009541--hachikuji--KAFKA-13234--4eaa38931f/report.html

[hachikuji]

I ran the transaction tests again with --repeat 5. There were no failures: http://confluent-kafka-branch-builder-system-test-results.s3-us-west-2.amazonaws.com/2021-08-26--001.system-test-kafka-branch-builder--1630022023--hachikuji--KAFKA-13234--4eaa38931f/report.html.

[ijuma]

LGTM if we have validated that the updated system tests still work.

[hachikuji]

@ijuma Thanks. I will post test results once the run completes.

[showuon]

LGTM! It makes sense to wait for the under replicas partitions becomes 0 after restart the nodes.

[hachikuji]

@ijuma @showuon Thanks for reviews. I've reverted the changes to the upgrade/downgrade tests so that I can move them to a separate PR. I was seeing some compatibility issues with the URP command occasionally, but haven't had enough time to track them down. However, the changes seem stable for the transactions tests, so I'll go ahead and merge.