Fix clock scale changes on the first transition after keyguard root view is attached

Default value of BurnInModel will be emitted when keyguard root view is
attached, and will update until the transition in blueprint is
triggered, which causes the clock scale value change.

Bug: 421050099
Flag: com.android.systemui.shared.clock_reactive_smartspace_layout
Test: manual test transitions after folding/unfolding, e.g. go in and
out of AOD, have enhanced smartspace shown and disappeared

Change-Id: Ibeecc1651c0131d520e9b488ee21a59060e31778