Revert of Enable the bayesian bitrate estimator by default. (patchset #5 id:80001 of https://codereview.webrtc.org/2749803002/ )

Reason for revert:
Looks like this has caused multiple Android webrtc perf build bot failures in RampUpTest.UpDownUpTransportSequenceNumberRtx

Original issue's description:
> Enable the bayesian bitrate estimator by default.
>
> BUG=webrtc:6566, webrtc:7415
>
> Review-Url: https://codereview.webrtc.org/2749803002
> Cr-Commit-Position: refs/heads/master@{#17475}
> Committed: https://chromium.googlesource.com/external/webrtc/+/c53a17f28e55c99dca7a2a47f09790af466e9334

TBR=terelius@webrtc.org,magjed@webrtc.org,stefan@webrtc.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=webrtc:6566, webrtc:7415

Review-Url: https://codereview.webrtc.org/2786913003
Cr-Original-Commit-Position: refs/heads/master@{#17476}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 7a3615b6b394bfe12a0ab528dee0dd33620e0e63
8 files changed