release-24.1: sql/row: fix updates of single-composite-column families

[michae2]

Backport 1/1 commits from #131869.

/cc @cockroachdb/release

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sql/row: fix updates of single-composite-column families

When updating a single-column family which contains what could be a composite value from the primary key, we still need to issue a Del even if the new value for the column is not composite, because the previous value might have been composite.

Fixes: #131860

Release note (bug fix): Fix a rare bug in which an update of a primary key column which is also the only column in a separate column family can sometimes fail to update the primary index. This bug has existed since v22.2. Requirements to hit the bug are:

1. A table with multiple column families.
2. A column family containing a single PK column.
3. That column family is not the first column family.
4. That column family existed before its column was in the PK.
5. That column must be of type FLOAT4/8, DECIMAL, JSON, collated string type, or array.
6. An update that changes that column from a composite value to a non-composite value.

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Release justification: low-risk fix for a rare corruption bug.

[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