Improve Scream on low bitrate

Reduce min_ref_window to 1000 bytes

Use stricter pacing for 15s after last congestion event regardless of event

Remove scaling close to mss since it reduce rampup and adaption speed.

Ensure ref_window_i_ is updated to the ref_window_ before a reduction. Continue to allow it to be changed after every time ref window increase and then decrease.

Bug: webrtc:447037083
Change-Id: I5a6cafa35c09d20b06bb9f05a22d97f687002fde
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/449921
Reviewed-by: Björn Terelius <terelius@webrtc.org>
Commit-Queue: Per Kjellander <perkj@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#46967}