Remove KCP (fixes #4737) (#4741)

cmd/stdiscosrv/apisrv.go

@@ -336,7 +336,7 @@ func fixupAddresses(remote net.IP, addresses []string) []string {
 		ip := net.ParseIP(host)
 		if host == "" || ip.IsUnspecified() {
 			// Do not use IPv6 remote address if requested scheme is ...4
-			// (i.e., tcp4, kcp4, etc.)
+			// (i.e., tcp4, etc.)
 			if strings.HasSuffix(uri.Scheme, "4") && remote.To4() == nil {
 				continue
 			}

cmd/syncthing/usage_report.go

@@ -199,7 +199,6 @@ func reportData(cfg configIntf, m modelIntf, connectionsService connectionsIntf,
 		res["limitBandwidthInLan"] = opts.LimitBandwidthInLan
 		res["customReleaseURL"] = opts.ReleasesURL != "https://upgrades.syncthing.net/meta.json"
 		res["restartOnWakeup"] = opts.RestartOnWakeup
-		res["customStunServers"] = len(opts.StunServers) == 0 || opts.StunServers[0] != "default" || len(opts.StunServers) > 1
 
 		folderUsesV3 := map[string]int{
 			"scanProgressDisabled":    0,