[QA] oc_appconfig stores passwords unencrypted

Seen in oc 10.8.0-beta2

#38728 encrypts mount passwords stored in the database. But there are more locations where passwords are stored unencrypted:

MariaDB [owncloud]> select * from oc_appconfig where configkey like '%pass%';
+-----------+------------------------+--------------+
| appid     | configkey              | configvalue  |
+-----------+------------------------+--------------+
| user_ldap | s01ldap_agent_password | b3duY2xvdWQ= |
| user_ldap | s02ldap_agent_password | UEBzc3cwcmQ= |
+-----------+------------------------+--------------+
2 rows in set (0.005 sec)

These two are base64 encoded, and can be trivially converted back to their plain text representation (owncloud and P@ssw0rd)

Start by tracing how the user_ldap s01ldap_agent_password and s02ldap_agent_password values are stored in oc_appconfig, using the behavior from #38728 as a reference. Done means these passwords are encrypted at rest rather than merely base64 encoded; verify the resulting database values and the LDAP configuration behavior.