Always reparent SurfacePackage in setChildSurfacePackage.

Currently, SurfaceView#setChildSurfacePackage only reparents a
provided SurfacePackage when there is no SurfaceControl already
present. This can lead to the SurfacePackage potentially never
being reparented.

This changelist addresses the issue by always reparenting the
SurfacePackage, following cleanup of the existing
SurfaceControl.

Bug: 197568243
Test: atest SurfaceControlViewHostTests#testCanReplaceSurfacePackage
Change-Id: Ib0bcfee5cb9801e1b1c4f1f300af9862141b12f3