Always start AuthController

Since device credential is now a first-class citizen, we need to ensure
that SystemUI is always responding to authentication requests. For example,
on devices without biometrics, applications that request authentication
with Authenticators.DEVICE_CREDENTIAL is still a valid request.

Bug: 149795050

Test: Remove /vendor/etc/permissions/android.hardware.fingerprint.xml,
      reboot. Go through CtsVerifier biometric section

Change-Id: I555aa5763deb31011eea46572272327f02470a02