Faster room joins: fix race in recalculation of current room state (#13151)

Bounce recalculation of current state to the correct event persister and
move recalculation of current state into the event persistence queue, to
avoid concurrent updates to a room's current state.

Also give recalculation of a room's current state a real stream
ordering.

Signed-off-by: Sean Quah <seanq@matrix.org>

tests/test_state.py

@@ -195,6 +195,8 @@ class StateTestCase(unittest.TestCase):
                 "get_state_resolution_handler",
                 "get_account_validity_handler",
                 "get_macaroon_generator",
+                "get_instance_name",
+                "get_simple_http_client",
                 "hostname",
             ]
         )