Only autoVerify at install for new hosts

Only autoVerify at install for new hosts

Re-run app link verification at update time only when the set of hosts
has expanded.  Intentionally revoke verify history when an app stops
using autoVerify, as a one-time measure to place it back into the
non-autoverify model for tracking the user's launch preferences.  If the
app starts using autoVerify again later, it behaves identically to an
app that has never done so before.

Bug: 151475497
Bug: 146204120
Test: described on master CL

Merged-In: I200d85085ce79842a3ed39377d1f75ec381c8991
Change-Id: Ibaf087946966ad82d60c7b255e3ee75990716b63