release-22.2: kvserver: deflake test store capacity after split

[kvoli]

Backport 1/1 commits from #98515.

/cc @cockroachdb/release

---

This commit defales TestStoreCapacityAfterSplit. Previously it was possible for the replica load stats which underpins Capacity to be reset. The reset caused the recording duration to fall short of min stats duration, which led to a 0 value being reported for writes in store capacity.

This commit bumps the manual clock twice and removes redundant leaseholder checks within a retry loop. The combination of these two changes makes the test much less likely to flake.

The test is now unskipped.

dev test pkg/kv/kvserver -f TestStoreCapacityAfterSplit -v --stress
...
4410 runs so far, 0 failures, over 6m10s

Resolves: #92677
Release note: None

---

Fixes: #111738
Release justification: Test only change.

[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?

[cockroach-teamcity]

This change is 

[kvoli]

Acceptance failure looks unrelated:

unknown input: {"Time":"2023-10-13T10:50:06.447131085-04:00","Action":"start","Package":"github.com/cockroachdb/cockroach/pkg/acceptance","Test":"PackageLevel","Elapsed":0,"Output":""}

[andrewbaptist]

[kvoli]

TYFTR