Fix crash in ACC#convertTo/FromTranslucent.

Fix a regression from Ic1cda79da37162cca2a1a3fbc73311cc325b3874.
The original CL is to create a new transition to ensure the visibility
of the activity would be correct if the activity is playing a
transition, so it is not necessary to create transition if another
transition is collecting.

Bug: 267616097
Test: atest ActivityVisibilityTests ActivityTransitionTest
Change-Id: Idcdf7c3fb2f44deb0c641ee4b2cd5c763abba473