release-23.1.9-rc: kvserver: disable enqueue into repl q on span cfg update

[kvoli]

Backport 1/2 commits from #108725.

/cc @cockroachdb/release

---

Replicas were enqueued into the replicate queue, upon the store
receiving a span config update which could affect the replica. The
replicate queue shouldQueue is relatively more expensive than other
queues.
Introduce the cluster setting
kv.enqueue_in_replicate_queue_on_span_config_update.enabled, which when
set to true, enables queuing up replicas on span config updates; when
set to false, disables queuing replicas on span config updates.
By default, this settings is set to false.

Resolves: #108724

Release note (ops change): Introduce the
kv.enqueue_in_replicate_queue_on_span_config_update.enabled cluster
setting. When set to true, stores in the cluster will enqueue replicas
for replication changes, upon receiving config updates which could
affect the replica. This setting is off by default. Enabling this
setting speeds up how quickly config triggered replication changes
begin, but adds additional CPU overhead. The overhead scales with the
number of leaseholders.

---

Release justification: Disables patch which introduced CPU overhead
in clusters with many ranges.

[cockroach-teamcity]

This change is 

[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?

[kvoli]

CI failing due to Free disk space requirements could not be met. I'll retry the CI later/early tomorrow.

[kvoli]

TYFTR!