Revert of Change TWCC send interval to reduce overhead on low BW situations. (patchset #10 id:200001 of https://codereview.webrtc.org/2381833003/ )

Reason for revert:
Breaks internal tests.

Original issue's description:
> Change TWCC send interval to reduce overhead on low BW situations.
>
> BUG=webrtc:6442
>
> Committed: https://crrev.com/861e9374640eaa37ba5d905e3e0971df04b4fc9e
> Cr-Commit-Position: refs/heads/master@{#14910}

TBR=minyue@webrtc.org,stefan@webrtc.org,michaelt@webrtc.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=webrtc:6442

Review-Url: https://codereview.webrtc.org/2468413009
Cr-Commit-Position: refs/heads/master@{#14933}