release-23.1: kvserver: don't report unreachable followers when quiesced

[erikgrinaker]

Backport 1/1 commits from #104212.

/cc @cockroachdb/release

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Previously, Replica.tick() could mark a Raft follower as unreachable even if the replica was quiesced, transitioning it to StateProbe. This in turn can prevent lease transfers, which require the target to be up-to-date. However, with the range quiesced, the follower wouldn't transition back to healthy until the leader unquiesced for some reason.

We normally don't quiesce with a follower that isn't caught up, and applying internal state transitions while the range is quiesced is problematic since it won't have a chance to react to those state transitions.

This patch instead defers marking the follower as unreachable until the next tick, whenever the range unquiesces, such that the leader can detect the follower's recovery. Since ranges aren't allowed to quiesce when they have outstanding ready events or log entries, we're likely to detect unavailability and mark the follower as unavailable on the next tick before quiescing anyway.

Resolves #103828.

Epic: none
Release note: None

[blathers-crl]

Thanks for opening a backport.

Please check the backport criteria before merging:

• Patches should only be created for serious issues or test-only changes.
• Patches should not break backwards-compatibility.
• Patches should change as little code as possible.
• Patches should not change on-disk formats or node communication protocols.
• Patches should not add new functionality.
• Patches must not add, edit, or otherwise modify cluster versions; or add version gates.

If some of the basic criteria cannot be satisfied, ensure that the exceptional criteria are satisfied within.

• 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.
• The PM and TL on the team that owns the changed code have signed off that the change obeys the above rules.

Add a brief release justification to the body of your PR to justify this backport.

Some other things to consider:

• What did we do to ensure that a user that doesn’t know & care about this backport, has no idea that it happened?
• Will this work in a cluster of mixed patch versions? Did we test that?
• If a user upgrades a patch version, uses this feature, and then downgrades, what happens?

[blathers-crl]

It looks like your PR touches production code but doesn't add or edit any test code. Did you consider adding tests to your PR?

_{🦉 Hoot! I am a Blathers, a bot for CockroachDB. My owner is dev-inf.}

[cockroach-teamcity]

This change is