backend/drm: rollback pending CRTC state on test commit
backend/drm: rollback pending CRTC state on test commit

A test commit doesn't apply the pending state.

The CRTC state will be populated again if the compositor decides to
perform a regular commit afterwards.

SirCmpwn/wlroots,swaywm/wlroots,ascent12/wlroots,ascent12/wlroots,swaywm/wlroots