Stop checking FDE password cache

Now that FDE is no longer supported, checking the FDE password cache
will never accomplish anything.  Remove this check from Keyguard, and
remove the supporting code from LockSettingsService.

Bug: 208476087
Change-Id: If1bb80dfcc015aeea19916a88c89a4067e6ada32
(cherry picked from commit e9b69111b203bec8266f096a0fec942b570da97a)
Merged-In: If1bb80dfcc015aeea19916a88c89a4067e6ada32
4 files changed