Docs update usage of force option when running the restore raketask

Current documentation of backup_restore.md shows use of force=yes but only for 'Do not ask if the authorized_keys file should get regenerated.'. This option will also stop the yes/no prompt message which confirms

Before restoring the database we recommend removing all existing
tables to avoid future upgrade problems. Be aware that if you have
custom tables in the GitLab database these tables and all data will be
removed.

Do you want to continue (yes/no)? no