release-23.1: ttl: use better defaults for some session variables

[yuzefovich]

Backport 1/2 commits from #118330.

/cc @cockroachdb/release

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This commit fixes some problems that we've seen around internally-executed queries issued by the TTL jobs, present before 23.2. In particular, on 23.1 and prior releases we used Go defaults for the session data parameters for internally-executed queries, which can differ from the defaults set by CRDB. As a result, query plans could be suboptimal as we've seen in a couple of recent escalations. This bug has been fixed on 23.2 proper (we now use CRDB defaults for all session variables except for one), and on 23.1 and prior this commit applies a targeted fix only to the TTL queries. In particular, the following overrides are now set:

• reorder_joins_limit to the default value of 8
• optimizer_use_histograms and optimizer_use_multi_col_stats are both set to true.

On 23.2 and later only optimizer_use_histograms needs to be updated since it's the only exception mentioned above. However, I chose to keep all 3 in the same commit so that it can be backported more easily to 23.1, and the following commit will revert the other 2 on 23.2 and later.

Touches: #102954.
Fixes: #118129.

Release note (bug fix): Internal queries issued by the TTL jobs should now use optimal plans. The bug has been present since at least 22.2 version.

Release justification: bug fix.

[blathers-crl]

Thanks for opening a backport.

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[blathers-crl]

It looks like your PR touches production code but doesn't add or edit any test code. Did you consider adding tests to your PR?

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[cockroach-teamcity]

This change is 

[mgartner]

Reviewed 6 of 6 files at r1, all commit messages.
Reviewable status: complete! 1 of 0 LGTMs obtained (waiting on @rafiss)

[yuzefovich]

blathers backport release-23.1.15-rc

[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 setting reviewers, but backport branch blathers/backport-release-23.1.15-rc-118496 is ready: POST https://api.github.com/repos/cockroachdb/cockroach/pulls/118564/requested_reviewers: 422 Reviews may only be requested from collaborators. One or more of the teams you specified is not a collaborator of the cockroachdb/cockroach repository. []

Backport to branch release-23.1.15-rc failed. See errors above.

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