Make the resumed activity visible

A resumed activity was added to stopping activity lists while making
it invisible without having state changes. Before dealing with the
stopping activity list and resume it again results in the visibility
still kept in invisible state.

This CL ensures that the RESUMED activity can be visible again when
no longer be occluded. Moreover, delete the duplicated remove
stopping action because makeVisibleIfNeeded() already did.

Bug: 163360820
Test: atest VrDisplayTests#testVrActivityReLaunch
Change-Id: I6e43825ca3825f059a7ac556fff7efe9f8999b63