Fix postgres ID sequences broken by recreate-table (#15015)

Fix postgres ID sequences broken by recreate-table (#15015)

* Fix postgres ID sequences broken by recreate-table

Unfortunately there is a subtle problem with recreatetable on postgres which
leads to the sequences not being renamed and not being left at 0.

Fix #14725

Signed-off-by: Andrew Thornton <art27@cantab.net>
* let us try information_schema instead

Signed-off-by: Andrew Thornton <art27@cantab.net>
* try again

Signed-off-by: Andrew Thornton <art27@cantab.net>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>
Co-authored-by: 6543 <6543@obermui.de>