clusterversion,kvserver,sql: remove AutoStatsTableSettings

[celiala]

This commit removes the 22.1 AutoStatsTableSettings version gate.

Cleanup was done following guidance from 21.2 cleanup:

For the most part, if the gates were just simple if !version.IsActive { return x } or something, I just removed the block, and even if it was a little more complicated, like args = [x]; if version { args = append(args, y) }; foo(args) I still tried to mostly inline it such that it looked natural (i.e. remove that append and make it args = [x, y]).

However for just a couple more complicated cases that were referring to <21.2 versions that needed to be replaced when those were deleted, I added a placeholder clusterversion.TODOPre21_2 alias for 21.2. Replacing those calls with this alias shouldn't change their behavior -- it was already always true, since the code today should never run in a <21.2 cluster -- but means we can delete those older versions in the meantime and then the owners of these bits can decide how to update them.

Partially addresses #80663

Release note: None
Release justification: remove old version gates.

[cockroach-teamcity]

This change is 

[msirek]

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

[celiala]

TFTR!

FYI @msirek that I'm removing TestAutoStatsTableSettingsDisallowedOnOldCluster -- please scream and shout if this should be kept!

Removing TestAutoStatsTableSettingsDisallowedOnOldCluster since:

• it was failing (expected "feature not available yet" error but instead got nil)
• it depended on both ClusterLocksVirtualTable and AutoStatsTableSettings -- both of which are 22.1 version gates

[msirek]

It should be OK. This change will only be in 22.2. My understanding is, upgrades are only allowed one minor release at a time, so any nodes running an old version of CRDB would be on 22.1 at the oldest, which does support AutoStatsTableSettings.

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

[celiala]

TestLogic_external_connection_privileges is failing all of #85937 , #85938 , #85939, so I'm going to assume that it's not related to changes in this commit.

off_test.runfiles/com_github_cockroachdb_cockroach/pkg/sql/logictest/testdata/logic_test/external_connection_privileges:24: SELECT * FROM system.privileges
        expected:
            root      /externalconn/foo  {ALL}         {}
            testuser  /externalconn/foo  {DROP,USAGE}  {}
        but found (query options: "") :
            testuser  /externalconn/foo  {DROP,USAGE}  {}
            root      /externalconn/foo  {ALL}         {}

[celiala]

TFTR!

bors r=msirek

[craig]

Build failed (retrying...):

• Bazel Essential CI (Cockroach)

[craig]

Build succeeded:

• Bazel Essential CI (Cockroach)