chore: re-enable mxdeliv test

This reverts commit d51137c.

Author: j-g00da

src/relay_minitest/test_relay.py

@@ -79,7 +79,6 @@ def test_delivery_port_blocked(
         lines = relayadmin.wait_for_journal_match("deferred|delivery attempt failed")
         lp.indent(lines.splitlines()[-1])
 
-    @pytest.mark.skip(reason="mxdeliv currently disabled on chatmail/relay")
     def test_one_on_one_http_only(
         self, cmfactory, cmfactory2, relayadmin2, lp
     ):