Fix repair stream ID reporting for RTX pairing. (#4369)

If RTX stream got a packet before primary stream, the pairing was not
getting set up properly.

pkg/sfu/interceptor/rtx.go

@@ -92,7 +92,7 @@ func (f *RTXInfoExtractorFactory) SetStreamInfo(ssrc uint32, mid, rid, rsid stri
 			if info.mid == mid && info.rsid == rid {
 				repairSsrc = repair
 				baseSsrc = ssrc
-				repairSid = info.rid
+				repairSid = rid
 				delete(f.streams, repair)
 				break
 			}
@@ -115,6 +115,8 @@ func (f *RTXInfoExtractorFactory) SetStreamInfo(ssrc uint32, mid, rid, rsid stri
 	}
 }
 
+// ------------------------------------------
+
 type RTXInfoExtractor struct {
 	interceptor.NoOp
 
@@ -143,6 +145,8 @@ func (u *RTXInfoExtractor) BindRemoteStream(info *interceptor.StreamInfo, reader
 	}
 }
 
+// ------------------------------------------
+
 type rtxInfoReader struct {
 	tryTimes  int
 	reader    interceptor.RTPReader