KAFKA-7484: fix suppression integration tests

[vvcephei]

The test data is based at time 0 (aka 1970), but the broker was started at time now.
This caused the log cleaner to delete the test data if the tests took slightly too long, despite its generous default configuration.

Committer Checklist (excluded from commit message)

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

[vvcephei]

@mjsax Do you think this is likely the fix for the recent test failures?

It seems to work for me, but the absence of failure is no proof...

[mjsax]

I assume it will work -- but frankly not 100% sure. Don't know exactly, how the broker advances it's mocked time internally.

[vvcephei]

I also considered setting the broker's log retention to max_int hours, but I figured we should make the minimal change that we think will fix the problem (otherwise, we'll never learn what the actual fix was)

[guozhangwang]

For Integration tests, the Embedded broker will not actively advance its MockTime unless MockTime.sleep() is called explicitly.

[guozhangwang]

The change lgtm, waiting for jenkins to pass

[vvcephei]

@guozhangwang @mjsax : the tests have passed.

[mjsax]

Merged to trunk and cherry-picked to 2.1 branch.

[vvcephei]

Thank you, @mjsax !