changefeedccl: fix kafka v2 sink does not allow negative GZIP compression levels less than zero

[yaothao]

Fix: Support for Negative GZIP Compression Levels in Kafka v2 Sink #136492

This update fixes a bug in the Kafka v2 sink where negative GZIP compression levels were not supported within the expected range of [-2, 9]. Previously, the v2 sink could not handle negative compression levels properly due to differences in the underlying compression libraries used between v1 and v2 sinks.

Background

Our Kafka v1 sink implementation, which relies on the sarama library, uses the klauspost/compress library that supports a compression level of -3. However, our v2 sink has transitioned to using franz-go, which utilizes the standard library's compression/gzip, and does not support the -3 level. This discrepancy led to confusion and a bug when using similar configurations across different sink versions.

Changes Made

• Compression Level Support: The Kafka v2 sink now properly supports compression levels in the range of [-2, 9], aligning with the capabilities of the Go standard library’s gzip package.

Documentation Changes Required

• Update Compression Level Documentation: It is necessary to update the documentation for Kafka GZIP compression levels. The current range needs to be adjusted to reflect the removal of -3 from the supported levels in the Kafka v2 sink documentation.

Testing

• Unit Tests: Comprehensive unit tests have been added and passed to confirm that the Kafka v2 sink now correctly handles all compression levels within the newly supported range.
  • All unit tests related to GZIP compression settings pass successfully.

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[cockroach-teamcity]

This change is 

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[asg0451]

Thanks for the contribution @yaothao. Can you take a look at what the bot has said here: #137646 (comment)

You may also want to check out our guidelines for commit messages:

https://cockroachlabs.atlassian.net/wiki/spaces/CRDB/pages/73072807/Git+Commit+Messages

[asg0451]

This looks good, just need to fix the things i mentioned in my last comment

[yaothao]

Thank you for your feedback, @asg0451. I have incorporated several suggestions from our Git Commit Messages guidelines. Regarding the comments on this pull request, I have already addressed the issue with multiple commits and made the necessary adjustments. As I continue to learn through the process, please let me know if there's anything else I might have missed or could enhance. Thank you for your time.