Do not start biometric auth if encrypted or lockdown

Moved isLockDown and isEncrypted to the final "shouldListen"
assignment to avoid potential future mistakes, since they should
never be overridden.

Bug: 79776455

Test: atest KeyguardUpdateMonitorTest
Test: Fingerprint/Face does not start when lockdown or encrypted
Change-Id: Ia36dcc82a382c2064bf8d82facaa5d381f075148