release-23.1: changefeedccl: add nil checking for avroDataRecord.refreshTypeMetadata

[wenyihu6]

Backport 1/1 commits from #119639.

/cc @cockroachdb/release

---

Previously, the "after" field was populated across all envelope formats.
However, in commit c00bf0f, row data was moved to the “after” field for envelope
= wrapped and to “record” field for other envelope formats. But the commit did
not add a nil check for registered.schema.after which is only populated for
wrapped envelope. registered.schema.after is now nil for other envelope
formats, and calling refreshTypeMetadata on it could lead to node panics. In
addition, this commit did not add the logic calling refreshTypeMetadata on the
registered.schema.record for other envelope formats. This patch addresses the
issue by adding a defensive nil check before invoking refreshTypeMetadata and
adding refreshTypeMetadata for the record field when it's set to match the
original intents of the commit.

Fixes: #119428
Release note: None

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Release justification: low risk 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.
• Backports should not change on-disk formats or node communication protocols.
• Backports should not add new functionality (except as defined
  here).
• Backports must not add, edit, or otherwise modify cluster versions; or add version gates.
• All backports must be reviewed by the owning areas TL and one additional
  TL. For more information as to how that review should be conducted, please consult the backport
  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).
• The PM and TL on the team that owns the changed code have signed off that the change obeys the above rules.
• Your backport must be accompanied by a post to the appropriate Slack
  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 

[andyyang890]

Reviewable status: complete! 1 of 0 LGTMs obtained (waiting on @jayshrivastava, @rharding6373, @stevendanna, and @wenyihu6)

---

pkg/ccl/changefeedccl/encoder_test.go line 1115 at r1 (raw file):

	cdcTest(t, testFn, feedTestForceSink("cloudstorage"))
}

nit: extra newline

---

pkg/ccl/changefeedccl/encoder_test.go line 1187 at r1 (raw file):

	}
}

nit: extra newline

[wenyihu6]

Friendly ping on the PR review here : ) Hoping to merge it before the next branch cut.

[wenyihu6]

@stevendanna do you mind taking a quick look at this PR? Backporting requires stamps from 2 TLs.

[stevendanna]

Thanks for the explanation!

This is a clear bug fix for a bug that causes a node panic, which I view as serious.