WifiNetworHistory: Don't persist QNS blacklist

QNS blacklists network temporarily by setting the network status. Reset
this value when we bootup so that this not persisted. This is especially
needed as we move away from using wall clock for blacklist time.

Also,
Remove the unused blacklist timestamp key from network history parsing.

BUG: 28824635
Change-Id: Ie64c11f358b2e3389ec419cfcfdde8bb04298dd4
TEST: Compliles & unit-test passes
1 file changed
tree: 294bd8c583f570d125d9ed0c2dc1f7be9cf5da53
  1. service/
  2. tests/