LDAP: make sure app meta data is not deleted from database when deleting configuration with empty prefix

apps/user_ldap/lib/helper.php

@@ -81,7 +81,8 @@ class Helper {
 			DELETE
 			FROM `*PREFIX*appconfig`
 			WHERE `configkey` LIKE ?
-				AND appid = "user_ldap"
+				AND `appid` = "user_ldap"
+				AND `configkey` NOT IN ("enabled", "installed_version", "types", "bgjUpdateGroupsLastRun")
 		');
 		$res = $query->execute(array($prefix.'%'));