Improve integration tests

Co-authored-by: Julien Salleyron <julien.salleyron@gmail.com>

integration/resources/compose/udp.yml

@@ -2,20 +2,21 @@ version: "3.8"
 services:
   whoami-a:
     image: traefik/whoamiudp:latest
-    command: -name whoami-a
+    command:
+      - -name
+      - whoami-a
 
   whoami-b:
     image: traefik/whoamiudp:latest
-    command: -name whoami-b
+    command:
+      - -name
+      - whoami-b
 
   whoami-c:
     image: traefik/whoamiudp:latest
-    command: -name whoami-c
+    command:
+      - -name
+      - whoami-c
 
   whoami-d:
     image: traefik/whoami
-
-networks:
-  default:
-    name: traefik-test-network
-    external: true