sql: don't parallelize *any* FK and unique checks containing locking

[michae2]

sql, execbuilder: move plan flags from planTop to planComponents

Execbuild produces a sql.planComponents containing the main query
plan, plus plans for any subqueries, checks, and cascades. In the normal
SQL code path (sql.(*optPlanningCtx).runExecBuilder) we copy this
planComponents into a sql.planTop, which then is decorated with extra
information gathered from the Builder.

However, there are other users of execbuild that only work with the
planComponents, and don't have a planTop. In the next commit, one such
user, PlanAndRunCascadesAndChecks, needs to see some of the plan flags
set when building FK check plans, but doesn't have access to the Builder
which gathered those plans.

To solve this, this commit moves plan flags from the planTop to
planComponents, and then refactors the execbuilder and exec factory to
set some of these flags when creating the planComponents.

Informs: #118720

Epic: None

Release note: None

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sql: don't parallelize any FK and unique checks containing locking

In #111896 we disallowed parallel execution of FK and unique checks that
contain locking, to avoid usage of LeafTxns. But #111896 only considered
checks built during planning of the main query, and overlooked checks
built during planning of FK cascades.

This commit also considers checks built during planning of FK cascades.

Fixes: #118720

Epic: None

Release note (bug fix): This commit fixes an internal error with message
like: "LeafTxn ... incompatible with locking request" that occurs when
performing an update under read committed isolation which cascades to a
table with multiple other foreign keys.

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sql: rename *ContainsNonDefaultKeyLocking to *ContainsLocking

"Default" locking here simply means no locking. I find this convention
of saying "non-default key locking" a little verbose and confusing.

Epic: None

Release note: None

[cockroach-teamcity]

This change is 

[michae2]

My plan is to backport the first two commits after this has baked on master for a few weeks.

[yuzefovich]

Nice find!

Reviewed 13 of 13 files at r1, 2 of 2 files at r2, 7 of 7 files at r3, all commit messages.
Reviewable status: complete! 1 of 0 LGTMs obtained (waiting on @nvanbenschoten)

[michae2]

Thanks!

bors r=yuzefovich

[craig]

Build succeeded:

• Bazel Essential CI (Cockroach)

[blathers-crl]

Encountered an error creating backports. Some common things that can go wrong:

1. The backport branch might have already existed.
2. There was a merge conflict.
3. The backport branch contained merge commits.

You might need to create your backport manually using the backport tool.

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error creating merge commit from 5021627 to blathers/backport-release-23.2-118722: POST https://api.github.com/repos/cockroachdb/cockroach/merges: 409 Merge conflict []

you may need to manually resolve merge conflicts with the backport tool.

Backport to branch 23.2.x failed. See errors above.

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