Fix DI issue

Signed-off-by: Joas Schilling <coding@schilljs.com>

lib/private/Group/Database.php

@@ -421,6 +421,8 @@ class Database extends ABackend
 	}
 
 	public function getDisplayName(string $gid): string {
+		$this->fixDI();
+
 		$query = $this->dbConn->getQueryBuilder();
 		$query->select('displayname')
 			->from('groups')
@@ -447,6 +449,8 @@ class Database extends ABackend
 			return false;
 		}
 
+		$this->fixDI();
+
 		$query = $this->dbConn->getQueryBuilder();
 		$query->update('groups')
 			->set('displayname', $query->createNamedParameter($displayName))