release-23.2: sql/stats: fix panic catching in the stats cache, show histogram

[rytaft]

Backport 1/1 commits from #135944.

/cc @cockroachdb/release

---

This commit removes a top-level panic catcher from GetTableStats in the stats
cache, and instead adds a couple of lower level panic catchers. The problems
with the top-level catcher are:

• There are other entry points into the stats cache besides GetTableStats, so
  it missed some cases.
• Because the stats cache contains shared state, condition variables, mutexes,
  etc, it was possible to get into a scenario where a panic would bypass
  important logic (such as broadcasting when a resource is available), but the
  panic would be caught at the top level and leave the cache in a bad state.

The new panic catchers are below the level of this shared state manipulation,
but also ensure that all paths into the stats cache that might panic are
covered.

This commit also adds panic catching to SHOW HISTOGRAM so that decoding errors
do not crash the process when running SHOW HISTOGRAM.

Fixes #135940

Release note (bug fix): Fixed an issue where corrupted table statistics could cause the cockroach process to crash.

[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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  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).
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• Your backport must be accompanied by a post to the appropriate Slack
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Also, please add a brief release justification to the body of your PR to justify this
backport.

[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 

[michae2]

Reviewed 2 of 2 files at r1, all commit messages.
Reviewable status: complete! 1 of 0 LGTMs obtained (waiting on @rytaft)