Vertically center SCM-eligible on warm launch

Currently, a landscape activity that is eligible for size compat
mode is vertically centered on cold launch, and when put into
size compat mode. Fix an issue introduced in a prior change,
where vertical centering is not applied on warm launch.

Bug: 207849112
Bug: 205682025
Test: atest com.android.server.wm.SizeCompatTests
Change-Id: Id72e6efae49963ac9b6dd89cbc8c99e3a85b67f2