Use _remote_is_local=True for local connection in synchronize (#40833)

* All instances of local connection should use _remote_is_local=True. Fixes #40551

* Switch to instance attribute for synchronize

* Add test that shows that synchronize _remote_is_local addresses tmpdir building

lib/ansible/plugins/action/synchronize.py

@@ -301,6 +301,9 @@ class ActionModule(ActionBase):
 
             new_connection = connection_loader.get('local', self._play_context, new_stdin)
             self._connection = new_connection
+            # Override _remote_is_local as an instance attribute specifically for the synchronize use case
+            # ensuring we set local tmpdir correctly
+            self._connection._remote_is_local = True
             self._override_module_replaced_vars(task_vars)
 
         # SWITCH SRC AND DEST HOST PER MODE