perf: Don't fetch full group object in AuthorizedGroupMapper

This is very expensive when multiple group backends are enabled as we
don't cache which groups is included in which backend unlike in the User
Manager.

Signed-off-by: Carl Schwan <carlschwan@kde.org>

Author: CarlSchwan

lib/private/Settings/AuthorizedGroupMapper.php

@@ -11,7 +11,6 @@
 use OCP\DB\Exception;
 use OCP\DB\QueryBuilder\IQueryBuilder;
 use OCP\IDBConnection;
-use OCP\IGroup;
 use OCP\IGroupManager;
 use OCP\IUser;
 
@@ -31,16 +30,14 @@ public function findAllClassesForUser(IUser $user): array {
 
 		/** @var IGroupManager $groupManager */
 		$groupManager = \OC::$server->get(IGroupManager::class);
-		$groups = $groupManager->getUserGroups($user);
-		if (count($groups) === 0) {
+		$groupIds = $groupManager->getUserGroupIds($user);
+		if (count($groupIds) === 0) {
 			return [];
 		}
 
 		$result = $qb->select('class')
 			->from($this->getTableName(), 'auth')
-			->where($qb->expr()->in('group_id', array_map(function (IGroup $group) use ($qb) {
-				return $qb->createNamedParameter($group->getGID());
-			}, $groups), IQueryBuilder::PARAM_STR))
+			->where($qb->expr()->in('group_id', $qb->createNamedParameter($groupIds, IQueryBuilder::PARAM_STR_ARRAY)))
 			->executeQuery();
 
 		$classes = [];