release-23.1: kvcoord: Restart ranges on a dedicated goroutine.

[miretskiy]

Backport 1/1 commits from #100189.

/cc @cockroachdb/release

---

Restart ranges on a dedicated goroutine (if needed).
Fix logic bug in stuck range handling.
Increase verbosity of logging to help debug mux rangefeed issues.

Informs #99560
Informs #99640
Informs #99214
Informs #98925
Informs #99092
Informs #99212
Informs #99910
Informs #99560

Release note: None
Release justification: bug fixes and observability fixes to the disabled by default functionality.

[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 

[erikgrinaker]

Do we really want to change the verbosity of these log entries on a release branch? I'm fine with temporarily enabling them on master, but wouldn't want to ship them in a release.

[miretskiy]

Do we really want to change the verbosity of these log entries on a release branch? I'm fine with temporarily enabling them on master, but wouldn't want to ship them in a release.

I'm okay w/ that. We had failures both on master and 23.1 -- and I hope to get more debugging information.
As it exists now, we cannot recommend this feature to be used in production, so it's all about debugging.
Furthermore, with the following fixes built on top of this change, it would be easier to backport them in the future.

[erikgrinaker]

Ok, your call.

[miretskiy]

bors r+

[craig]

🕐 Waiting for PR status (GitHub check) to be set, probably by CI. Bors will automatically try to run when all required PR statuses are set.

[miretskiy]

bors r-

[craig]

This PR was included in a batch that successfully built, but then failed to merge into release-23.1 (it was a non-fast-forward update). It will be automatically retried.

[miretskiy]

bors r-

[craig]

Canceled.