composer: update VtsDisplay dimensions

When the active config changes, the display dimension might change
as well, so we need to update it to match the active config.

Test: run composer 2.4 VTS
Bug: 185195256
Change-Id: Ie2671e61498d2501901885b2a9986ee1974bd641
Merged-In: Ie2671e61498d2501901885b2a9986ee1974bd641
(cherry picked from commit c8013854)