Stop calling LockPatternUtils.setVisiblePasswordEnabled()

Since the removal of support for Full Disk Encryption (FDE) in favor of
File Based Encryption (FBE), this method has been a no-op.

Bug: 208476087
Test: atest ShowPasswordPreferenceControllerTest.  Note,
      isAvailable_whenNotVisible_isFalse fails both before and after.
Change-Id: Ifb8fc93757366240cf37e4b9a600c2034302919e
Merged-In: Ifb8fc93757366240cf37e4b9a600c2034302919e
(cherry picked from commit bcee8ce1)