test/pytest: add missing import, remove unused import

Add missed import time and remove unused name import.

Signed-off-by: Alejo Sanchez <alejo.sanchez@scylladb.com>

Closes #12446

test/pylib/manager_client.py

@@ -9,7 +9,8 @@
    Manages driver refresh when cluster is cycled.
 """
 
-from typing import List, Optional, Callable, NamedTuple, Any
+from typing import List, Optional, Callable, Any
+from time import time
 import logging
 from test.pylib.rest_client import UnixRESTClient, ScyllaRESTAPIClient
 from test.pylib.util import wait_for