ci: remove e2e test RUN_COMPACTION

[xxchan]

I hereby agree to the terms of the RisingWave Labs, Inc. Contributor License Agreement.

What's changed and what's your intention?

Checklist

• I have written necessary rustdoc comments.
• I have added necessary unit tests and integration tests.
• I have added test labels as necessary.
• I have added fuzzing tests or opened an issue to track them.
• My PR contains breaking changes.
• My PR changes performance-critical code, so I will run (micro) benchmarks and present the results.
• My PR contains critical fixes that are necessary to be merged into the latest release.

Documentation

• My PR needs documentation updates.

Release note

[xxchan]

Discussed with @zwang28, the compaction test isn't very useful and we can remove it.

Here we removed it from the script, and pr.env isn't useful anymore and we can unify run-e2e-test.sh and e2e-test-serial.sh. @zwang28 will delete the code in kernel later.