fix: forget to add clean up back

Signed-off-by: yihong0618 <zouzou0208@gmail.com>

Author: yihong0618

Lib/test/test_pyrepl/test_unix_console.py

@@ -313,3 +313,6 @@ def test_wait_reentry_protection(self, _os_write):
         console._polling_thread = threading.current_thread()
         with self.assertRaisesRegex(RuntimeError, "can't re-enter readline"):
             console.wait(timeout=0)
+
+        console._polling_thread = None
+        console.restore()