fix(l10n): Don't use "All 1 participant"

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

lib/Chat/ChatManager.php

@@ -1030,13 +1030,20 @@ class ChatManager {
 		}
 		if ($search === '' || $this->searchIsPartOfConversationNameOrAtAll($search, $roomDisplayName)) {
 			$participantCount = $this->participantService->getNumberOfUsers($room);
-			$results[] = [
+
+			$atAllResult = [
 				'id' => 'all',
 				'label' => $roomDisplayName,
-				'details' => $this->l->n('All %n participant', 'All %n participants', $participantCount),
 				'source' => 'calls',
 				'mentionId' => 'all',
 			];
+
+			if ($participantCount > 1) {
+				// TRANSLATORS The string will only be used with more than 1 participant, so you can keep the "All" in all plural forms
+				$atAllResult['details'] = $this->l->n('All %n participant', 'All %n participants', $participantCount);
+			}
+
+			$results[] = $atAllResult;
 		}
 		return $results;
 	}

tests/integration/features/chat-2/mentions.feature

@@ -61,7 +61,7 @@ Feature: chat/mentions
       | roomName | room |
     Then user "participant1" gets the following candidate mentions in room "group room" for "" with 200
       | id           | label                    | source | mentionId    | details           |
-      | all          | room                     | calls  | all          | All 1 participant |
+      | all          | room                     | calls  | all          |                   |
 
   Scenario: get mentions in a group room
     When user "participant1" creates room "group room" (v4)

tests/php/Chat/ChatManagerTest.php

@@ -735,7 +735,7 @@ class ChatManagerTest extends TestCase {
 					'actor_id' => 'user',
 				])],
 				1,
-				[['id' => 'all', 'label' => 'test', 'source' => 'calls', 'mentionId' => 'all', 'details' => 'All 1 participant']],
+				[['id' => 'all', 'label' => 'test', 'source' => 'calls', 'mentionId' => 'all']],
 			],
 			[
 				'all',