Revert of Verify sender ssrc when receiving rtcp target bitrate (patchset #3 id:40001 of https://codereview.webrtc.org/3000373002/ )

Reason for revert:
Might be the root cause of an internal test failure.

Original issue's description:
> Verify sender ssrc when receiving rtcp target bitrate
>
> BUG=webrtc:8137
>
> Review-Url: https://codereview.webrtc.org/3000373002
> Cr-Commit-Position: refs/heads/master@{#19524}
> Committed: a7a4beb419

TBR=danilchap@webrtc.org,sprang@webrtc.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=webrtc:8137

Review-Url: https://codereview.webrtc.org/3005633002
Cr-Commit-Position: refs/heads/master@{#19529}

webrtc/modules/rtp_rtcp/source/rtcp_receiver.cc

@@ -688,10 +688,8 @@ void RTCPReceiver::HandleXr(const CommonHeader& rtcp_block,
   for (const rtcp::ReceiveTimeInfo& time_info : xr.dlrr().sub_blocks())
     HandleXrDlrrReportBlock(time_info);
 
-  if (xr.target_bitrate()) {
-    HandleXrTargetBitrate(xr.sender_ssrc(), *xr.target_bitrate(),
-                          packet_information);
-  }
+  if (xr.target_bitrate())
+    HandleXrTargetBitrate(*xr.target_bitrate(), packet_information);
 }
 
 void RTCPReceiver::HandleXrReceiveReferenceTime(uint32_t sender_ssrc,
@@ -724,13 +722,8 @@ void RTCPReceiver::HandleXrDlrrReportBlock(const rtcp::ReceiveTimeInfo& rti) {
 }
 
 void RTCPReceiver::HandleXrTargetBitrate(
-    uint32_t ssrc,
     const rtcp::TargetBitrate& target_bitrate,
     PacketInformation* packet_information) {
-  if (ssrc != remote_ssrc_) {
-    return;  // Not for us.
-  }
-
   BitrateAllocation bitrate_allocation;
   for (const auto& item : target_bitrate.GetTargetBitrates()) {
     if (item.spatial_layer >= kMaxSpatialLayers ||