opt: respect NO_INDEX_JOIN flag

[rytaft]

Prior to this commit, it was possible that the optimizer could
produce a plan with an index join even if the user hinted that
index joins should be avoided by using the NO_INDEX_JOIN hint. This
commit fixes that oversight, and we no longer plan an index join
in this case. This commit also adds assertions that an index join
is not planned if NO_INDEX_JOIN is used to prevent this bug from
recurring.

Fixes #85841

Release note (bug fix): Fixed an issue where the NO_INDEX_JOIN
hint could be ignored by the optimizer in some cases, causing it
to create a query plan with an index join.

[cockroach-teamcity]

This change is 

[michae2]

Nice!

Reviewed 8 of 8 files at r1, all commit messages.
Reviewable status: complete! 1 of 0 LGTMs obtained (waiting on @mgartner)

[rytaft]

TFTR!

bors r+

[craig]

This PR was included in a batch that was canceled, it will be automatically retried

[craig]

Build failed (retrying...):

• Bazel Essential CI (Cockroach)

[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 c3da919 to blathers/backport-release-21.2-85843: 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 21.2.x failed. See errors above.

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