Fix lockscreen notification launch animation

When launching a notification from the lockscreen, we immediately
start an app transition because the app is started in invisible
/stopped state. Then, we try to take a screenshot, but nothing
is visible yet because the AppWindowToken is hidden.

Furthermore this fixes a bug where we were starting a remote
animation too aggressively.

Test: Launch anything from lockscreen
Test: go/wm-smoke
Change-Id: Iea9366813fa5780460a9ab2738f2a17f65fbeb15
Fixes: 73187454