upgrades: update system.web_sessions migration to handle orphaned rows

[andyyang890]

This patch updates the system.web_sessions user ID migration to delete
orphaned rows (i.e. rows corresponding to users that have been dropped)
after backfilling user IDs. They need to be deleted since they block
the addition of the NOT NULL constraint on the column.

Part of #87079

Release note: None

[cockroach-teamcity]

This change is 

[rafiss]

just one comment, and everything else lgtm!

Reviewable status: complete! 0 of 0 LGTMs obtained (waiting on @andyyang890)

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pkg/upgrade/upgrades/web_sessions_table_user_id_migration.go line 48 at r1 (raw file):

}

const deleteRowsForDroppedUsersWebSessionsTableStmt = `

i'm more in favor of doing this after the backfill, and changing this query to

	DELETE FROM system.web_sessions
	WHERE user_id IS NULL

(it seems less expensive)

[andyyang890]

Reviewable status: complete! 0 of 0 LGTMs obtained (waiting on @rafiss)

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pkg/upgrade/upgrades/web_sessions_table_user_id_migration.go line 48 at r1 (raw file):

Previously, rafiss (Rafi Shamim) wrote…

i'm more in favor of doing this after the backfill, and changing this query to

	DELETE FROM system.web_sessions
	WHERE user_id IS NULL

(it seems less expensive)

Done.

[rafiss]

lgtm!

[rafiss]

oh nice, i forgot that we could have a limit here.

[andyyang890]

TFTR!

bors r=rafiss

[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 setting reviewers, but backport branch blathers/backport-release-23.1-100017 is ready: POST https://api.github.com/repos/cockroachdb/cockroach/pulls/100244/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 23.1.x failed. See errors above.

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