test(rpc-client): test_qr_securejoin_broadcast: Wait for incoming message before getting chatlist (#7442)

Fix flaky test by calling `get_broadcast()` after the message events
were received.

Alternative to #7437

Author: Hocuri

deltachat-rpc-client/tests/test_securejoin.py

@@ -140,15 +140,15 @@ def get_broadcast(ac):
         return chat
 
     def wait_for_broadcast_messages(ac):
-        chat = get_broadcast(ac)
+        snapshot1 = ac.wait_for_incoming_msg().get_snapshot()
+        assert snapshot1.text == "You joined the channel."
 
-        snapshot = ac.wait_for_incoming_msg().get_snapshot()
-        assert snapshot.text == "You joined the channel."
-        assert snapshot.chat_id == chat.id
+        snapshot2 = ac.wait_for_incoming_msg().get_snapshot()
+        assert snapshot2.text == "Hello everyone!"
 
-        snapshot = ac.wait_for_incoming_msg().get_snapshot()
-        assert snapshot.text == "Hello everyone!"
-        assert snapshot.chat_id == chat.id
+        chat = get_broadcast(ac)
+        assert snapshot1.chat_id == chat.id
+        assert snapshot2.chat_id == chat.id
 
     def check_account(ac, contact, inviter_side, please_wait_info_msg=False):
         # Check that the chat partner is verified.