Adds exception.Conflict handler to is_resource_delete function

Swift API get_objects returns 409 when object delete in progress.
HTTP 409 is converted to exception.Conflict and raised
Updated is_resource_deleted check to handle exception.Conflict
  and return False (Object is not deleted)
If the exception is not handled the test cases fails with the error
b'BucketAlreadyExists which is not correct status for a bucket
which is being deleted by the tempest tearDown call.

Closes-Bug: #1938583
Change-Id: I6957c3ee1f3d60e7b8cd34d3db89bb27347d08b7

tempest/lib/services/object_storage/object_client.py

@@ -28,6 +28,8 @@ class ObjectClient(rest_client.RestClient):
             self.get_object(container, object_name)
         except exceptions.NotFound:
             return True
+        except exceptions.Conflict:
+            return False
         return False
 
     def create_object(self, container, object_name, data,