Revert "Updated some docs for the delayed deprecation of legacy table creation; refs #22340."

This reverts commit a2e3c9694823d6d451d6dd234e9d416600aacc68.

The deprecation was moved back to 1.9 in
61da5f3f02f34810aaa6fcddac3808318a5b95c4.
Removed db.backends methods which only call super().