Fixed #32178 -- Allowed database backends to skip tests and mark expected failures.

Co-authored-by: Tim Graham <timograham@gmail.com>

tests/servers/test_liveserverthread.py

@@ -13,8 +13,6 @@ class LiveServerThreadTest(TestCase):
 
     def test_closes_connections(self):
         conn = connections[DEFAULT_DB_ALIAS]
-        if conn.vendor == 'sqlite' and conn.is_in_memory_db():
-            self.skipTest("the sqlite backend's close() method is a no-op when using an in-memory database")
         # Pass a connection to the thread to check they are being closed.
         connections_override = {DEFAULT_DB_ALIAS: conn}