Improve integration tests

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

integration/resources/compose/pebble.yml

@@ -2,14 +2,12 @@ version: "3.8"
 services:
   pebble:
     image: letsencrypt/pebble:v2.3.1
-    command: pebble --dnsserver traefik:5053
+    command:
+      - pebble
+      - --dnsserver
+      - host.docker.internal:5053
     environment:
       # https://github.com/letsencrypt/pebble#testing-at-full-speed
       PEBBLE_VA_NOSLEEP: 1
       # https://github.com/letsencrypt/pebble#invalid-anti-replay-nonce-errors
       PEBBLE_WFE_NONCEREJECT: 0
-
-networks:
-  default:
-    name: traefik-test-network
-    external: true