Foreman Maintain

Cloned from https://bugzilla.redhat.com/show_bug.cgi?id=2172540

Description of problem:

The "Restoring postgresql global objects" step in "foreman-maintain restore" is buggy:
- it's executing the restore as the "foreman" user who has not the sufficient permissions to perform the actions (modifying global objects requires superuser permission)
- it sometimes fails with 'password authentication failed for user "foreman"' as the password of the user is changed during the overall restore procedure

However, it's also not required, as the only thing it's supposed to do is to (re-)create the users in the database, but that's already handled by the Installer run that happens before the Globals Restore.

To avoid any further issues, we can drop this step completely and rely on the Installer for the management of the database users.