release-24.3: sql: fix edge case causing suboptimal generic query plans

[blathers-crl]

Backport 1/1 commits from #135228 on behalf of @mgartner.

/cc @cockroachdb/release

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This commit fixes a bug that caused suboptimal generic query plans to be
planned under all of the following conditions:

1. plan_cache_mode was set to force_custom_plan (the default).
2. A query was prepared and an ideal generic query plan was selected
   (i.e., it used the placeholder fast path).
3. New stats were collected, making the original plan stale and
   increasing the estimated row count of the root expression beyond
   maxRowCountForPlaceholderFastPath (10).
4. The prepared query was re-executed.

Fixes #135151

There is no release note because this bug does not exist in any
releases.

Release note: None

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Release justification: Critical bug fix.

[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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• Backports should not add new functionality (except as defined
  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).
• New code is protected by a conditional check that is trivial to verify and ensures that it only runs for opt-in clusters. State changes must be further protected such that nodes running old binaries will not be negatively impacted by the new state (with a mixed version test added).
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  channel (#db-backports-point-releases or #db-backports-XX-X-release) for awareness and discussion.

Also, please add a brief release justification to the body of your PR to justify this
backport.

[cockroach-teamcity]

This change is 

[rytaft]

Reviewed 2 of 2 files at r1, all commit messages.
Reviewable status: complete! 1 of 0 LGTMs obtained (waiting on @DrewKimball, @mgartner, and @michae2)