MINOR: Streams upgrade system test cleanup

[bbejeck]

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Summary of testing strategy (including rationale)
for the feature or bug fix. Unit and/or integration
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system tests should be considered for larger changes.

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[bbejeck]

This is a follow-up PR to perform the same clean-up from #7552

Ran all system tests http://confluent-kafka-branch-builder-system-test-results.s3-us-west-2.amazonaws.com/2019-10-21--001.1571679740--bbejeck--MINOR_clean_up_streams_upgrade_system_test--8e61da4/report.html

All tests ran. Note there is one failure, but it' unrelated to these changes. I'm currently investigating the failure.

ping @guozhangwang @mjsax

[guozhangwang]

The change lgtm modulo the test failure, ping @mjsax again.

[bbejeck]

Turns out the test failure was related to logging changes in #7537 and I just needed to update the expected log statements. I ran a new branch builder for the failing test

http://confluent-kafka-branch-builder-system-test-results.s3-us-west-2.amazonaws.com/2019-10-23--001.1571861801--bbejeck--MINOR_clean_up_streams_upgrade_system_test--e5f5697/report.html

The test is showing some flakiness, but it's unrelated to the changes in this PR and should be pursued in a separate follow-on effort.

[bbejeck]

ping @guozhangwang and @mjsax updated this

[abbccdda]

Why do we remove args in print?

[abbccdda]

Will we hit NPE in this case?

[bbejeck]

updated with changes from #7586 by @ableegoldman. Re-ran branch builder with 10 repeats and the version probing test passes now
http://confluent-kafka-branch-builder-system-test-results.s3-us-west-2.amazonaws.com/2019-10-23--001.1571868682--bbejeck--MINOR_clean_up_streams_upgrade_system_test--b626e9a/report.html

[guozhangwang]

LGTM! Please feel free to merge @bbejeck

[bbejeck]

Merged #7571 into trunk