Remove redundant (and dangerous) PIM sync code

* This code is no longer necessary as we now check whether an
  adapter is syncable before each sync
* This code also caused the referenced bug; the code did not
  expect individual mailboxes to have separate sync settings

Bug: 5368250
Change-Id: I1dc3b9e26f09219e99afeffc88bfac7be043b89e
1 file changed