Correctly import isabs from os.path (#45178)

The #45139 imported isabs from "airflow.www.app" - but isabs has
been added there fairly recently and it is anyhow stdlib's os.path
isabs - so it should be imported from there.

This breaks fab 1.5.2 backport compatibility tests, so we need to
cherry-pick it there alongside #45139

(cherry picked from commit 7002966)

providers/src/airflow/providers/fab/auth_manager/cli_commands/utils.py

@@ -20,14 +20,15 @@
 import os
 from contextlib import contextmanager
 from functools import lru_cache
+from os.path import isabs
 from typing import TYPE_CHECKING, Generator
 
 from flask import Flask
 
 import airflow
 from airflow.configuration import conf
 from airflow.exceptions import AirflowConfigException
-from airflow.www.app import isabs, make_url
+from airflow.www.app import make_url
 from airflow.www.extensions.init_appbuilder import init_appbuilder
 from airflow.www.extensions.init_session import init_airflow_session_interface
 from airflow.www.extensions.init_views import init_plugins