Revert "rtp sender: don't send BYE on deactivating streams"

This reverts commit a22c2a0c581cbe3f612f7a7d9fb9840186cc1e06.

Reason for revert: breaks upstream project

Original change's description:
> rtp sender: don't send BYE on deactivating streams
>
> as this breaks RTCP assumptions about SSRCs being no longer
> active as defined in
>   https://www.rfc-editor.org/rfc/rfc3550#section-6.6
>
> This should not be sent in reaction to temporarily disabling
> a stream via RTCRtpParameters.active as this does not mean that
> the participant is leaving the session as defined in
>   https://www.rfc-editor.org/rfc/rfc3550#section-6.3.7
> and does not indicate end of participation as defined in
>   https://www.rfc-editor.org/rfc/rfc3550#section-6.1
> which stipulates BYE should be the last packet sent from this SSRC.
>
> BUG=webrtc:11082
>
> Change-Id: Ia5144857f85303643146b0759184f0f3f50b66e4
> Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/273348
> Reviewed-by: Harald Alvestrand <hta@webrtc.org>
> Commit-Queue: Philipp Hancke <phancke@microsoft.com>
> Cr-Commit-Position: refs/heads/main@{#38059}

Bug: webrtc:11082
Change-Id: Iaaff0c0d7bb857fe9ce78ebcc716f3c6f1bc5c4a
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/275640
Reviewed-by: Henrik Boström <hbos@webrtc.org>
Reviewed-by: Tomas Gunnarsson <tommi@webrtc.org>
Commit-Queue: Philipp Hancke <phancke@microsoft.com>
Bot-Commit: rubber-stamper@appspot.gserviceaccount.com <rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/main@{#38097}

modules/rtp_rtcp/source/rtp_rtcp_interface.h

@@ -281,7 +281,7 @@ class RtpRtcpInterface : public RtcpFeedbackSenderInterface {
   // Returns the FlexFEC SSRC, if there is one.
   virtual absl::optional<uint32_t> FlexfecSsrc() const = 0;
 
-  // Sets sending status.
+  // Sets sending status. Sends kRtcpByeCode when going from true to false.
   // Returns -1 on failure else 0.
   virtual int32_t SetSendingStatus(bool sending) = 0;