header-custom finalmask: Remove headerConnMode headerReadAddrAware interface (#6193)

https://github.com/XTLS/Xray-core/pull/5920#issuecomment-4253108964

https://github.com/XTLS/Xray-core/pull/6193#issuecomment-4531875088

infra/conf/transport_internet.go

@@ -1734,11 +1734,17 @@ func (c *HeaderCustomUDP) Build() (proto.Message, error) {
 		})
 	}
 
-	return &custom.UDPConfig{
-		Client: client,
-		Server: server,
-		Mode:   c.Mode,
-	}, nil
+	if c.Mode == "standalone" {
+		return &custom.UDPStandaloneConfig{
+			Client: client,
+			Server: server,
+		}, nil
+	} else {
+		return &custom.UDPConfig{
+			Client: client,
+			Server: server,
+		}, nil
+	}
 }
 
 type Dns struct {

infra/conf/transport_test.go

@@ -195,8 +195,7 @@ func TestHeaderCustomUDPBuild(t *testing.T) {
 				"mode": "standalone"
 			}`,
 			Parser: parser,
-			Output: &finalmaskcustom.UDPConfig{
-				Mode: "standalone",
+			Output: &finalmaskcustom.UDPStandaloneConfig{
 				Client: []*finalmaskcustom.UDPItem{
 					{
 						RandMax: 255,