chore(pageserver): use kebab case for compaction algorithms

[skyzh]

Problem

Summary of changes

Checklist before requesting a review

• I have performed a self-review of my code.
• If it is a core feature, I have added thorough tests.
• Do we need to implement analytics? if so did you add the relevant metrics to the dashboard?
• If this PR requires public announcement, mark it with /release-notes label and add several sentences in this section.

Checklist before merging

• Do not forget to reformat commit message to not include the above checklist

[github-actions]

3132 tests run: 3005 passed, 0 failed, 127 skipped (full report)

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Flaky tests (2)

Postgres 15

• test_no_config[application/json]: debug
• test_no_config[None]: debug

Code coverage* (full report)

• functions: 31.3% (6414 of 20506 functions)
• lines: 48.0% (49323 of 102658 lines)

* collected from Rust tests only

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_{The comment gets automatically updated with the latest test results
ab3fff6 at 2024-05-22T21:36:39.674Z :recycle:}