performance: Avoid Recipient lookup.

We don't have to go to the database to get the Recipient
fields for `user_profile.recipient`.

See also 85ed6f332a from a little
over a year ago--it's very similar.

zerver/lib/actions.py

@@ -2647,7 +2647,11 @@ def get_recipient_from_user_profiles(
     assert recipient_profiles_map
     if len(recipient_profiles_map) == 1:
         [user_profile] = recipient_profiles_map.values()
-        return user_profile.recipient
+        return Recipient(
+            id=user_profile.recipient_id,
+            type=Recipient.PERSONAL,
+            type_id=user_profile.id,
+        )
 
     # Otherwise, we need a huddle.  Make sure the sender is included in huddle messages
     recipient_profiles_map[sender.id] = sender

zerver/tests/test_example.py

@@ -376,7 +376,7 @@ class TestQueryCounts(ZulipTestCase):
             )
 
         # The assert_length helper is another useful extra from ZulipTestCase.
-        self.assert_length(queries, 16)
+        self.assert_length(queries, 15)
 
 
 class TestDevelopmentEmailsLog(ZulipTestCase):

zerver/tests/test_users.py

@@ -799,7 +799,7 @@ class QueryCountTest(ZulipTestCase):
                         acting_user=None,
                     )
 
-        self.assert_length(queries, 85)
+        self.assert_length(queries, 84)
         self.assert_length(cache_tries, 27)
 
         peer_add_events = [event for event in events if event["event"].get("op") == "peer_add"]