Fix smartspace flickering when back from clock customization

This is due to multiple times of callback messages sent to the lock
screen preview renderer.
By removing redundent messages, the flickers are gone.

Test: See bug.
Bug: 416057623
Flag: com.android.systemui.shared.new_customization_picker_ui
Change-Id: I661a84131e04388d26fbb651f3ea9013c458e4f4