Remove more FDE methods from StorageManager

Now that these methods are no longer called, and none of them are a
public API or have @UnsupportedAppUsage, they can be removed.

inCryptKeeperBounce() actually had one known app user via reflection,
despite the method not having @UnsupportedAppUsage.  However, that user
only made the call if Build.VERSION.SDK_INT < VERSION_CODES.P, so it is
not being used anymore.

Bug: 208476087
Change-Id: Idc218e5f355bb61257b07cf5b5b6df5f4c6ece11