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 e9b69111b2)
Merged-In: If1bb80dfcc015aeea19916a88c89a4067e6ada32