Fix enrolled face id can't be deleted when changing device rotation

then pressing back key

Handling the back key to enable remove-button state when face
deleting dialog appears.

Bug: 323277209

Test: manually check the reproducible steps:

Pre-Condition (Skip if not available):
1. make sure face unlock has been set
2. enable auto-rotate

STEPS TO REPRODUCE:
1. go to "Face unlock" page
2. click "Delete face model"
3. rotate to landscape mode
4. swipe back then observe

Change-Id: I5e3a06229390609deb42544f545ec9a21d374245