release-22.1: physicalplan: don't combine render nodes into one processor

[DrewKimball]

Backport 1/1 commits from #97554.

/cc @cockroachdb/release

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During planning for a render node, the physical planning logic checks whether the last created processor rendered its own expressions, adds its render expressions to the processor if not. The check is necessary to handle the case when expressions in a parent render reference those from a child render.

However, render nodes also handle projecting input columns: both removing them and reordering them. Correct planning of the processors depends on the columns at each step being in a particular order. Since physical planning didn't check whether the existing processor projected its columns in some way, the parent render could be combined with its child. This could lead to panics in the parent render expressions when the columns weren't projected as expected. This patch fixes the issue by adding the projection check before allowing the render planning code to add to the previous processor.

Fixes #95633

Release note (bug fix): Fixed a rare bug existing since before 22.1 that
could cause a projected expression to replace column references with the
wrong values.

Release Justification: low-risk for internal error during distsql planning

[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 

[yuzefovich]

Reviewed 6 of 6 files at r1, all commit messages.
Reviewable status: complete! 0 of 0 LGTMs obtained (waiting on @DrewKimball)

[DrewKimball]

Thanks!