SAP: Fix below issues during internal testing

1. Remove wait for shutdown to complete on main
   thread. Perform cleanup for handler and quit
   looper from closeService running on worker
   thread on first SHUTDOWN message.
   Check and allow posting of SHUTDOWN message
   only if later doesnt not already exists in
   mSessionStatusHandler message queue.

  CRs-Fixed: 982857

Change-Id: I42245dfb11a7750c5cde8213181e03defcfeedb4