chore: Remove redundant condition spotted by psalm

Signed-off-by: Côme Chilliet <come.chilliet@nextcloud.com>

Author: come-nc

lib/private/User/Manager.php

@@ -377,10 +377,8 @@ public function searchKnownUsersByDisplayName(string $searcher, string $pattern,
 				);
 
 			}
-			if (is_array($backendUsers)) {
-				foreach ($backendUsers as $uid => $displayName) {
-					$users[] = $this->getUserObject($uid, $backend);
-				}
+			foreach ($backendUsers as $uid => $displayName) {
+				$users[] = $this->getUserObject($uid, $backend);
 			}
 		}