Config: Outbound proxy config no need to be nested (#5124)

Like https://github.com/XTLS/Xray-core/commit/eda8be601f56c788b1ad176c7d68d8e2ce22c7ca

infra/conf/vless_test.go

@@ -57,6 +57,39 @@ func TestVLessOutbound(t *testing.T) {
 				},
 			},
 		},
+		{
+			Input: `{
+				"address": "example.com",
+				"port": 443,
+				"id": "27848739-7e62-4138-9fd3-098a63964b6b",
+				"flow": "xtls-rprx-vision-udp443",
+				"encryption": "none",
+				"level": 0
+			}`,
+			Parser: loadJSON(creator),
+			Output: &outbound.Config{
+				Vnext: []*protocol.ServerEndpoint{
+					{
+						Address: &net.IPOrDomain{
+							Address: &net.IPOrDomain_Domain{
+								Domain: "example.com",
+							},
+						},
+						Port: 443,
+						User: []*protocol.User{
+							{
+								Account: serial.ToTypedMessage(&vless.Account{
+									Id:         "27848739-7e62-4138-9fd3-098a63964b6b",
+									Flow:       "xtls-rprx-vision-udp443",
+									Encryption: "none",
+								}),
+								Level: 0,
+							},
+						},
+					},
+				},
+			},
+		},
 	})
 }