interdeparturethreshold should be 0 or a very small value like in google webrtc C++ code

[narayanaraorao]

In pkg/gcc/arrival_group_accumulator.go, interDepartureThreshold is 5 * time.Millisecond, whereas google C++ implementation uses 0 here. https://webrtc.googlesource.com/src//+/d090952628606228afa47c842812927f15227290/modules/congestion_controller/goog_cc/inter_arrival_delta.cc?autodive=#125

If we believe performance is an issue, we should use a very small value, like 100 microseconds. Otherwise, this introduces a large variation in delay, which occasionally causes delay estimator to signal overuse when there is no actual overuse.