Revert "Reduce overshoot in 1 pass rate control"

This reverts commit 212f6183.

Further testing shows that the overshoot accumulation/damping is too
aggressive on some clips. Allowing the accumulated overshoot to
decay and limiting to damping to golden frames shows some promise.
But some clips show significant overshoot in the buffer window, so
I think this still needs work.

Change-Id: Ic02a9ca34f55229f9cc04786f4fab54cdc1a3ef5