release-23.2.12-rc: kvserver: compact liveness range periodically

[iskettaneh]

Backport 1/1 commits from #129827.

/cc @cockroachdb/release

---

This commit adds a cluster setting (turned off by default) that sets the period at which manual liveness range compactions are done.

This is done in a goroutine rather than in MVCC GC queue because:

1. This is meant to be a stop gap as this in not needed in 24.3 onwards. Therefore, a simple change like this should achieve the goal.

2. The MVCC GC queue runs against leaseholder replicas only. This means that we need to send a compaction request to the other liveness replicas.

Fixes: #128968

Epic: None

Release note: None

Release justification: Help reduce point tombstone accumulation on the liveness range

[blathers-crl]

Thanks for opening a backport.

Please check the backport criteria before merging:

• Backports should only be created for serious
  issues or test-only changes.
• Backports should not break backwards-compatibility.
• Backports should change as little code as possible.
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• Backports should not add new functionality (except as defined
  here).
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  policy.

If your backport adds new functionality, please ensure that the following additional criteria are satisfied:

• There is a high priority need for the functionality that cannot wait until the next release and is difficult to address in another way.
• The new functionality is additive-only and only runs for clusters which have specifically “opted in” to it (e.g. by a cluster setting).
• New code is protected by a conditional check that is trivial to verify and ensures that it only runs for opt-in clusters. State changes must be further protected such that nodes running old binaries will not be negatively impacted by the new state (with a mixed version test added).
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Also, please add a brief release justification to the body of your PR to justify this
backport.

[cockroach-teamcity]

This change is 

[andrewbaptist]