Check the strongAuthTracker for lockdown instead of LockPatternUtils

LockPatternUtils and the StrongAuthTracker check for
lockdown may be out of sync, so always check the
KeyguardUpdateMonitor's strong auth tracker for
lockdown.

Test: atest KeyguardViewMediatorTest
Test: pin an app; lock down device;
observe keyguard always shows (repeat 10x times)
Bug: 438973280
Flag: EXEMPT CVE_FIX

(cherry picked from commit 5c25e76eb886ad3508103b486b146b6920c8c651)
Cherrypick-From: https://googleplex-android-review.googlesource.com/q/commit:0f786445c61e9bf8c9eacae9a8075f05ea9d36dc
Merged-In: I076f5a8cacd14fc8ab8893aedf98ff831a9c195f
Change-Id: I076f5a8cacd14fc8ab8893aedf98ff831a9c195f