Add traces for otp redaction for apps

Add traces around projection start/stop and notification updates that
trigger app hiding

Bug: 317251408
Flag: ACONFIG com.android.server.notification.sensitive_notification_app_protection DISABLED
Test: atest SensitiveContentProtectionManagerServiceTest
Change-Id: I783f9207cc6a3f951e5959d53bac6eda8d965c51