fix(cinder-understack): clean up a library's looping call tasks

Take each task that a library's looping call has in it and call stop and
then drain the list. This should allow us to remove a running library
instance.

Author: cardoe

python/cinder-understack/cinder_understack/dynamic_netapp_driver.py

@@ -237,9 +237,9 @@ def _remove_svm_lib(self, svm_name: str, svm_lib: NetAppMinimalLibrary):
         """Remove resources for a given SVM library."""
         # TODO: Need to free up resources here.
         LOG.info("Removing resources for SVM library %s", svm_name)
-        # Stop any looping calls if they exist
-        if hasattr(svm_lib, "loopingcalls"):
-            LOG.info("Stopping looping call for SVM library %s", svm_name)
+        for task in svm_lib.loopingcalls.tasks:
+            task.looping_call.stop()
+        svm_lib.loopingcalls.tasks = []
 
     def _refresh_svm_libraries(self):
         return self._actual_refresh_svm_libraries(context.get_admin_context())