Remove TrackSender.ParticipantIdentity since it's unused (#738)

Just introduced this in #736 and realized the interface change comes
with a bunch of unintended consequences, so reverting this addition.

pkg/rtc/mediatracksubscriptions.go

@@ -144,7 +144,6 @@ func (t *MediaTrackSubscriptions) AddSubscriber(sub types.LocalParticipant, wr *
 		codecs,
 		wr,
 		t.params.BufferFactory,
-		sub.Identity(),
 		subscriberID,
 		t.params.ReceiverConfig.PacketBufferSize,
 		LoggerWithTrack(sub.GetLogger(), trackID),

pkg/service/wire_gen.go

@@ -1,7 +1,8 @@
 // Code generated by Wire. DO NOT EDIT.
 
 //go:generate go run github.com/google/wire/cmd/wire
-//+build !wireinject
+//go:build !wireinject
+// +build !wireinject
 
 package service
 

pkg/sfu/downtrack.go

@@ -33,7 +33,6 @@ type TrackSender interface {
 	// ID is the globally unique identifier for this Track.
 	ID() string
 	SubscriberID() livekit.ParticipantID
-	SubscriberIdentity() livekit.ParticipantIdentity
 }
 
 const (
@@ -109,19 +108,18 @@ type ReceiverReportListener func(dt *DownTrack, report *rtcp.ReceiverReport)
 // - closed
 // once closed, a DownTrack cannot be re-used.
 type DownTrack struct {
-	logger             logger.Logger
-	id                 livekit.TrackID
-	subscriberIdentity livekit.ParticipantIdentity
-	subscriberID       livekit.ParticipantID
-	bound              atomic.Bool
-	kind               webrtc.RTPCodecType
-	mime               string
-	ssrc               uint32
-	streamID           string
-	maxTrack           int
-	payloadType        uint8
-	sequencer          *sequencer
-	bufferFactory      *buffer.Factory
+	logger        logger.Logger
+	id            livekit.TrackID
+	subscriberID  livekit.ParticipantID
+	bound         atomic.Bool
+	kind          webrtc.RTPCodecType
+	mime          string
+	ssrc          uint32
+	streamID      string
+	maxTrack      int
+	payloadType   uint8
+	sequencer     *sequencer
+	bufferFactory *buffer.Factory
 
 	forwarder *Forwarder
 
@@ -194,7 +192,6 @@ func NewDownTrack(
 	codecs []webrtc.RTPCodecCapability,
 	r TrackReceiver,
 	bf *buffer.Factory,
-	subIdentity livekit.ParticipantIdentity,
 	subID livekit.ParticipantID,
 	mt int,
 	logger logger.Logger,
@@ -210,16 +207,15 @@ func NewDownTrack(
 	}
 
 	d := &DownTrack{
-		logger:             logger,
-		id:                 r.TrackID(),
-		subscriberIdentity: subIdentity,
-		subscriberID:       subID,
-		maxTrack:           mt,
-		streamID:           r.StreamID(),
-		bufferFactory:      bf,
-		receiver:           r,
-		upstreamCodecs:     codecs,
-		kind:               kind,
+		logger:         logger,
+		id:             r.TrackID(),
+		subscriberID:   subID,
+		maxTrack:       mt,
+		streamID:       r.StreamID(),
+		bufferFactory:  bf,
+		receiver:       r,
+		upstreamCodecs: codecs,
+		kind:           kind,
 	}
 	d.forwarder = NewForwarder(d.kind, d.logger)
 
@@ -329,8 +325,6 @@ func (d *DownTrack) Codec() webrtc.RTPCodecCapability { return d.codec }
 // StreamID is the group this track belongs too. This must be unique
 func (d *DownTrack) StreamID() string { return d.streamID }
 
-func (d *DownTrack) SubscriberIdentity() livekit.ParticipantIdentity { return d.subscriberIdentity }
-
 func (d *DownTrack) SubscriberID() livekit.ParticipantID { return d.subscriberID }
 
 // Sets RTP header extensions for this track
@@ -1371,7 +1365,6 @@ func (d *DownTrack) DebugInfo() map[string]interface{} {
 
 	return map[string]interface{}{
 		"SubscriberID":        d.subscriberID,
-		"Subscriber":          d.subscriberIdentity,
 		"TrackID":             d.id,
 		"StreamID":            d.streamID,
 		"SSRC":                d.ssrc,