Moves airflow import in deprecated pod_generator to local

The import might be invoked when K8S executor starts with sentry on
and it might lead to circular imports

Related: apache#31442

airflow/providers/cncf/kubernetes/pod_generator_deprecated.py

@@ -31,8 +31,6 @@
 import re2
 from kubernetes.client import models as k8s
 
-from airflow.utils.hashlib_wrapper import md5
-
 MAX_POD_ID_LEN = 253
 
 MAX_LABEL_LEN = 63
@@ -71,6 +69,8 @@ def make_safe_label_value(string):
     way from the original value sent to this function, then we need to truncate to
     53 chars, and append it with a unique hash.
     """
+    from airflow.utils.hashlib_wrapper import md5
+
     safe_label = re2.sub(r"^[^a-z0-9A-Z]*|[^a-zA-Z0-9_\-\.]|[^a-z0-9A-Z]*$", "", string)
 
     if len(safe_label) > MAX_LABEL_LEN or string != safe_label: