Clear mFrameTimelineVsyncId after transaction is applied

Without clearing the mFrameTimelineVsyncId, there can be stale tokens
that get reused, thereby resulting in wrong classification of janks.
This change cleans up the existing code and calls clear(), which
does a clean clear of all the states.

Bug: 171329973
Test: dumpsys SurfaceFlinger --frametimeline on cold starting an app
Change-Id: Ia27520fc6dbb79a122fed40ad963ef470bc2ae35