opt: add EliminateConstValueSubquery normalization rule

[mgartner]

The EliminateConstValueSubquery normalization rule replaces a subquery
with a constant value when the subquery's input is a single-rows,
single-column Values expression with a constant value. This enables
further optimization of the query.

Fixes #104218

Release note (performance improvement): The optimizer now produces more
efficient query plans in some cases for queries with subqueries and
user-defined functions.

[cockroach-teamcity]

This change is 

[DrewKimball]

Nice idea, I'm surprised we haven't done this before.

Reviewed 9 of 9 files at r1, all commit messages.
Reviewable status: complete! 1 of 0 LGTMs obtained (waiting on @mgartner and @rharding6373)

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pkg/sql/opt/norm/rules/subquery.opt line 10 at r1 (raw file):

[EliminateConstValueSubquery, Normalize]
(Subquery
    (Values $rows:*) &

I think you could move the logic into optgen like this if you want:

(Values [ (Tuple [ $constant(Const) ]) ])

[mgartner]

Reviewable status: complete! 0 of 0 LGTMs obtained (and 1 stale) (waiting on @DrewKimball and @rharding6373)

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pkg/sql/opt/norm/rules/subquery.opt line 10 at r1 (raw file):

Previously, DrewKimball (Drew Kimball) wrote…

I think you could move the logic into optgen like this if you want:

(Values [ (Tuple [ $constant(Const) ]) ])

Brilliant. That's much better.

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pkg/sql/logictest/testdata/logic_test/apply_join line 470 at r2 (raw file):

            (VALUES (tab_54747.col_95055)) AS tab_54752 (col_95061)
          WHERE
            (SELECT random()::INT) < tab_54752.col_95061

The new rule was eliminating a subquery, which broken this test. So I changed this to a non-constant so that the rule won't fire.

[rharding6373]

Very nice!

Reviewable status: complete! 1 of 0 LGTMs obtained (and 1 stale) (waiting on @DrewKimball)

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[mgartner]

TFTRs!

bors r+

[craig]

Build succeeded:

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