Remove redundant test assertion for sender visibility in ChatServiceTest

backend/src/test/java/com/alttd/altitudeweb/services/chat/ChatServiceTest.java

@@ -105,7 +105,6 @@ class ChatServiceTest {
         EventUser receiver = new EventUser(receiverUuid, List.of(), null);
         EventUser other = new EventUser(UUID.randomUUID(), List.of(), null);
 
-        assertTrue(messageForUser.get(sender).contains("private message"), "Sender should see their own message");
         assertTrue(messageForUser.get(receiver).contains("private message"), "Receiver should see the message");
         assertFalse(messageForUser.get(other).contains("private message"), "Others should not see private message");
     }