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/Headers/WebRTC/RTCBitrateAllocationStrategy.h

@@ -1,32 +0,0 @@
-/*
- *  Copyright 2017 The WebRTC project authors. All Rights Reserved.
- *
- *  Use of this source code is governed by a BSD-style license
- *  that can be found in the LICENSE file in the root of the source
- *  tree. An additional intellectual property rights grant can be found
- *  in the file PATENTS.  All contributing project authors may
- *  be found in the AUTHORS file in the root of the source tree.
- */
-
-#import <WebRTC/RTCMacros.h>
-#import <WebRTC/RTCMediaStreamTrack.h>
-
-NS_ASSUME_NONNULL_BEGIN
-
-namespace rtc {
-
-class BitrateAllocationStrategy;
-}
-
-RTC_EXPORT
-@interface RTCBitrateAllocationStrategy : NSObject
-
-- (instancetype)init NS_UNAVAILABLE;
-- (instancetype)initWith:(rtc::BitrateAllocationStrategy*)strategy;
-
-/** Native bitrate allocation strategy. */
-@property(nonatomic, readonly) rtc::BitrateAllocationStrategy* strategy;
-
-@end
-
-NS_ASSUME_NONNULL_END