Revert "BWE allocation strategy allows controlling of bitrate allocation with WEBRTC external logic."

This reverts commit 54d1da13a584680ae80a1f229291e5bb7e76e6e1.

Reason for revert: Breaking tests

Original change's description:
> BWE allocation strategy allows controlling of bitrate allocation with WEBRTC external logic.
> 
> This CL implements the main logic and IOS appRTC integration.
> 
> Unit tests and Android appRTC will be in separate CL.
> 
> Bug: webrtc:8243
> Change-Id: If8e5195294046a47316e9fade1b0dfec211155e1
> Reviewed-on: https://webrtc-review.googlesource.com/4860
> Commit-Queue: Alex Narest <alexnarest@webrtc.org>
> Reviewed-by: Niels Moller <nisse@webrtc.org>
> Reviewed-by: Stefan Holmer <stefan@webrtc.org>
> Reviewed-by: Taylor Brandstetter <deadbeef@webrtc.org>
> Cr-Commit-Position: refs/heads/master@{#20329}

TBR=deadbeef@webrtc.org,nisse@webrtc.org,stefan@webrtc.org,alexnarest@webrtc.org

Change-Id: I5be1da78f360f72be66f9d56dd6b88c1cc13e963
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: webrtc:8243
Reviewed-on: https://webrtc-review.googlesource.com/12560
Reviewed-by: Lu Liu <lliuu@webrtc.org>
Commit-Queue: Lu Liu <lliuu@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#20330}

sdk/objc/Framework/Classes/PeerConnection/RTCPeerConnection.mm

@@ -21,7 +21,6 @@
 #import "RTCRtpReceiver+Private.h"
 #import "RTCRtpSender+Private.h"
 #import "RTCSessionDescription+Private.h"
-#import "WebRTC/RTCBitrateAllocationStrategy.h"
 #import "WebRTC/RTCLogging.h"
 
 #include <memory>
@@ -386,15 +385,6 @@ void PeerConnectionDelegateAdapter::OnIceCandidatesRemoved(
   return _peerConnection->SetBitrate(params).ok();
 }
 
-- (void)setBitrateAllocationStrategy:
-        (RTCBitrateAllocationStrategy *_Nullable)bitrateAllocationStrategy {
-  if (bitrateAllocationStrategy)
-    _peerConnection->SetBitrateAllocationStrategy(
-        std::unique_ptr<rtc::BitrateAllocationStrategy>(bitrateAllocationStrategy.strategy));
-  else
-    _peerConnection->SetBitrateAllocationStrategy(nullptr);
-}
-
 - (BOOL)startRtcEventLogWithFilePath:(NSString *)filePath
                       maxSizeInBytes:(int64_t)maxSizeInBytes {
   RTC_DCHECK(filePath.length);