Don't play transitions if keyguard didn't register

This could happen:

  (a) if something went wrong in early setup
  (b) if SysUI crashed and received transitions while restarting

Bug: 302538471
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:8a20c08f0db20b3461903ecd387bd63b5dd7f149)
Merged-In: Iff0f1c4af9e1da96b7bbd04bd45da9f5330fd9b1
Change-Id: Iff0f1c4af9e1da96b7bbd04bd45da9f5330fd9b1