release-22.2: sql,tree: improve function resolution efficiency

[blathers-crl]

Backport 2/2 commits from #89317 on behalf of @ajwerner.

/cc @cockroachdb/release

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sql: prevent allocations by avoiding some name pointers

We don't need pointers for these names. They generally won't escape.

sql,tree: change SearchPath to avoid allocations

The closure-oriented interface was forcing the closures and the variables they
referenced to escape to the heap. This change, while not beautiful, ends up being
much more efficient.

name                                         old time/op    new time/op    delta
SQL/MultinodeCockroach/Upsert/count=1000-16    20.4ms ±11%    18.9ms ± 8%   -7.47%  (p=0.000 n=20+19)

name                                         old alloc/op   new alloc/op   delta
SQL/MultinodeCockroach/Upsert/count=1000-16    10.1MB ±29%     9.8MB ±29%     ~     (p=0.231 n=20+20)

name                                         old allocs/op  new allocs/op  delta
SQL/MultinodeCockroach/Upsert/count=1000-16     56.3k ± 7%     50.2k ±10%  -10.81%  (p=0.000 n=19+19)

Release note: None

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Release justification: nice win for very little cost

[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]

Thanks! Should this go in 22.2.0 too?

Reviewed 6 of 6 files at r1, 7 of 7 files at r2, all commit messages.
Reviewable status: complete! 0 of 0 LGTMs obtained (waiting on @chengxiong-ruan)

[ajwerner]

Is it a GA blocker?

[yuzefovich]

I guess not.