Use approachLayout for squishiness

That way, we can report the height of QQS measured without squishiness.
This is needed because QuickSettingsController and NPVC need the
measured height at the final step of the animation.

Test: manual
Bug: 369657526
Flag: com.android.systemui.qs_ui_refactor_compose_fragment
Change-Id: Ie66b64b0d71021ee59aca28f4024c3841e5f7660