Fix overcounting after end in case of incomplete callbacks

The original intent of the code was to wait until we get one frame
with end vsync id or beyond end vsync id with both HWUI and SF
callbacks being reported such that we can ensure that our data
collection is complete.

However, the logic unintentionally started janky frames after the
end in case there were callbacks missing on the end vsync id,
leading to skewed metrics.

Also expand unit tests to verify jank number results.

Test: FrameTrackerTest
Fixes: 223787365
Change-Id: I90948d9ab2d44bf805e78f5611e072a7cc9ae0cd