Keep early vsync-offsets for at least two frames after transaction

Imagine the following sequence, in which vsync-sf is usually 4ms
behind vsync-app.
- Vsync-app fires. The app sends a transaction with early wakeup.
- Vsync-sf fires immediately after early wakeup is received,
before the regular 4ms delay.
- Vsync-sf resets itself to vsync-app+4ms as the transaction was
handled.
- Repeat 1, but now the app was a bit delayed and sends the early
wakeup late, such that the time used to do GL comp isn't enough to
avoid jank.

To fix this, we apply a low pass filter for transaction-caused
early wake and keep it early for at least 2 frames.

Test: Open/close apps, inspect systraces and verify wake-up times
Bug: 78611607
Change-Id: I74b0d88a4d95ca5b6d24950e14e3d6a9379f2714