Do not try to revert adding members if Member added message is not sent

This operation may itself fail
and with timestamps reverting addition is non-trivial.

Author: link2xt

src/chat.rs

@@ -3728,10 +3728,8 @@ pub(crate) async fn add_contact_to_chat_ex(
         msg.param.set_cmd(SystemMessage::MemberAddedToGroup);
         msg.param.set(Param::Arg, contact_addr);
         msg.param.set_int(Param::Arg2, from_handshake.into());
-        if let Err(e) = send_msg(context, chat_id, &mut msg).await {
-            remove_from_chat_contacts_table(context, chat_id, contact_id).await?;
-            return Err(e);
-        }
+        send_msg(context, chat_id, &mut msg).await?;
+
         sync = Nosync;
         // TODO: Remove this compat code needed because Core <= v1.143:
         // - doesn't accept synchronization of QR code tokens for unpromoted groups, so we also send

src/receive_imf/tests.rs

@@ -4931,7 +4931,10 @@ async fn test_protected_group_add_remove_member_missing_key() -> Result<()> {
     assert!(add_contact_to_chat(alice, group_id, alice_fiona_id)
         .await
         .is_err());
-    assert!(!is_contact_in_chat(alice, group_id, alice_fiona_id).await?);
+    // Sending the message failed,
+    // but member is added to the chat locally already.
+    assert!(is_contact_in_chat(alice, group_id, alice_fiona_id).await?);
+
     // Now the chat has a message "You added member fiona@example.net. [INFO] !!" (with error) that
     // may be confusing, but if the error is displayed in UIs, it's more or less ok. This is not a
     // normal scenario anyway.