rabbit_ct_client_helpers: Add a timeout to `open_channel/2`

[Why]
Exactly like in commit b165adb958, we
don't need to wait indefinitely for a channel to open. If it lasts,
there is a problem.

There is probably a weakness/bug in that basic channels manager that
would explain those indefinite operations though.

deps/rabbitmq_ct_client_helpers/src/rabbit_ct_client_helpers.erl

@@ -217,6 +217,8 @@ open_channel(Config, Node) ->
     Pid ! {open_channel, self()},
     receive
         Ch when is_pid(Ch) -> Ch
+    after 60_000 ->
+        ct:fail("Timed out waiting for connection to open")
     end.
 
 open_connection_and_channel(Config) ->