Don't show face messages if fp messages are showing

Test: enroll face and fingeprint; wear a mask; intentionally
fail fingerprint, observe that the FP message always shows
instead of the face covering detected message (from face auth)
Test: atest KeyguardIndicationContrllerTest KeyguardMessageAreaControllerTest
Fixes: 302877651
Flag: None

Change-Id: I0df461f529b8853a3faf74017a704962eb56e1ef