This removes the unused field trials
`WebRTC-SimulcastScreenshareUpswitchHysteresisPercent` and
`WebRTC-SimulcastScreenshareUpswitchHysteresisPercent` as well as the
`video_hysteresis` and `screenshare_hysteresis` parameters in
`WebRTC-VideoRateControl`.
The hysteresis parameters in `WebRTC-StableTargetRate` are currently
left, their future is unclear...
Bug: webrtc:9734
Change-Id: I9e6bbe4b630a0501d365bf69e87e65164c500122
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/269207
Reviewed-by: Emil Lundmark <lndmrk@webrtc.org>
Auto-Submit: Erik Språng <sprang@webrtc.org>
Commit-Queue: Erik Språng <sprang@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#37635}