bottom-most-compaction: use in test_gc_feedback + fix bugs

[skyzh]

Problem

Adds manual compaction trigger; add gc compaction to test_gc_feedback

Part of #8002

test_gc_feedback[debug-pg15].logical_size: 50 Mb
test_gc_feedback[debug-pg15].physical_size: 2269 Mb
test_gc_feedback[debug-pg15].physical/logical ratio: 44.5302 
test_gc_feedback[debug-pg15].max_total_num_of_deltas: 7 
test_gc_feedback[debug-pg15].max_num_of_deltas_above_image: 2 
test_gc_feedback[debug-pg15].logical_size_after_bottom_most_compaction: 50 Mb
test_gc_feedback[debug-pg15].physical_size_after_bottom_most_compaction: 287 Mb
test_gc_feedback[debug-pg15].physical/logical ratio after bottom_most_compaction: 5.6312 
test_gc_feedback[debug-pg15].max_total_num_of_deltas_after_bottom_most_compaction: 4 
test_gc_feedback[debug-pg15].max_num_of_deltas_above_image_after_bottom_most_compaction: 1

Summary of changes

• Add the manual compaction trigger
• Use in test_gc_feedback
• Add a guard to avoid running it with retain_lsns
• Fix: Do schedule_compaction_update after compaction
• Fix: Supply deltas in the correct order to reconstruct value

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]

2998 tests run: 2872 passed, 0 failed, 126 skipped (full report)

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Code coverage* (full report)

• functions: 32.8% (6888 of 21016 functions)
• lines: 50.3% (53885 of 107171 lines)

* collected from Rust tests only

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_{The comment gets automatically updated with the latest test results
1433f80 at 2024-06-25T22:26:45.819Z :recycle:}

[problame]

better title for this PR would be:

bottom-most compaction: use in test_gc_feedback + fix bugs this revealed

And please enumerate / mention the list of bugs fixed in the PR description

[problame]

Please create a work issue for the pitr_interval: ... stuff and track it in your epic!