Update string kg_face_sensor_privacy_enabled

Shorten kg_face_sensor_privacy_enabled to prevent string truncated at
keyguard lock screen.

Bug: 226046215
Test: Check string is not truncated on extra case (max font_scale, max
density, enable home control and gpay on lockscreen)
Change-Id: Id1ae933fe5c48e54a49beb17a08d5994b30d52b5

Change-Id: I72e83f133c63fb897e7c18e4cf0d65d47c282c13