Revert "Set a relative layer instead of reparenting launch animations."

This reverts commit f50caa76.

Reason for revert: partial revert to CP fix to b/404507270. The end state is the same as currently at ToT, but need to have cherry-pickable CLs for branches that are in CP mode.

Change-Id: I049b5de5065e4d877bfa835eaa3a97d724ada2cc