KAFKA-12950 Replace EasyMock and PowerMock with Mockito for KafkaStream

[wycccccc]

Development of EasyMock and PowerMock has stagnated while Mockito continues to be actively developed. With the new Java cadence, it's a problem to depend on libraries that do bytecode generation and are not actively maintained. In addition, Mockito is also easier to use.KAFKA-7438

build.gradle will update after other related issues are merged, avoid conflicts.Minor changes to the source code.I think this is inevitable.If there is a better solution to avoid changes, suggestions are welcome.

Committer Checklist (excluded from commit message)

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

[ijuma]

@wycccccc Can you please fix the conflict? @chia7712 How do you feel about this PR, is it close to being ready to be merged?

[chia7712]

How do you feel about this PR, is it close to being ready to be merged?

I need to take another look after those conflicts are fixed.

[wycccccc]

@chia7712 The conflict has been resolved, let me know if you have any situation.

[ijuma]

Btw, this is the only Streams test that is disabled with Java 16 and newer: https://github.com/apache/kafka/blob/trunk/build.gradle#L389

[ijuma]

@chia7712 Conflicts are resolved. :)

[divijvaidya]

@wycccccc are you planning to work further on this PR?