Summary:
As title, use mocked dead server to simulate fail delete, and invoke axonlog spool.

In order to get tw task id from SR in test, update mock SMC in TargetHooks to populate tw_task_id.

Reviewed By: stuclar

Differential Revision: D32395294

fbshipit-source-id: f90cad524f044b5c1c7aafe184eeb9751413556e