fix QS header for new ConstraintLayout version

With new ConstraintLayout versions layout_constrainedWidth was causing the view to assume match_parent width.

As MotionScene supports importing external layouts, we're not loading them at runtime anymore.

Also, the transition for large_screen_header_constraint is not used anymore, as initial and final constraint were the same.

Bug: 259933125
Test: CombinedShadeHeaderConstraintsTest and manual
Change-Id: I3961d9f4311c96b5d0663e1700fca78be5e6544b