[ticket/11367] Migrator throws error if migrations table does not exist

Force load_migration_state to not throw errors if the table does not exist.

PHPBB3-11367
[ticket/11367] Always freeresult

PHPBB3-11367
Merge remote-tracking branch 'EXreaction/ticket/11367' into develop

# By Nathan Guse (1) and Nathaniel Guse (1)
# Via Nathan Guse
* EXreaction/ticket/11367:
  [ticket/11367] Always freeresult
  [ticket/11367] Migrator throws error if migrations table does not exist