Remove GetFeedbackInterval in sender side BWE.
And changed the minimum increase rate in |aimd_rate_control| to prevent the system from overusing on short twcc report send interval.

BUG=webrtc:6514

Review-Url: https://codereview.webrtc.org/2407143002
Cr-Original-Commit-Position: refs/heads/master@{#17794}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 8490f8af2112f7dfd45ce4009b05e167b2cae565
7 files changed