Fixes for a couple of strict mode violations.

- Removing from call log and trashing voicemails were both operating on
  ui thread.
- Decision here is not to finish until after the post execute completes.
- I could go further and test the result of the delete, and show a toast
  if the delete doesn't work, but for now leaving that work for later.

Bug: 5113695
Bug: 5098527
Change-Id: I5937de2e5c3da3794439f3fa510276b799162b0d