[2.2.x] Fixed #30193, Refs #28478 -- Avoided PostgreSQL connection health checks on initialization.

This addressed a regression introduced by a96b901932 as identified by Ran Benita.
Backport of 7071f8f272 from master

tests/backends/postgresql/tests.py

@@ -134,6 +134,12 @@ class Tests(TestCase):
         finally:
             new_connection.close()
 
+    def test_connect_no_is_usable_checks(self):
+        new_connection = connection.copy()
+        with mock.patch.object(new_connection, 'is_usable') as is_usable:
+            new_connection.connect()
+        is_usable.assert_not_called()
+
     def _select(self, val):
         with connection.cursor() as cursor:
             cursor.execute('SELECT %s', (val,))