Drop temporary docker-dind network workarounds in GitLab CI

Remove FF_NETWORK_PER_BUILD, the service alias, and the custom DNS
daemon flags from the docker jobs; they were only needed for a
temporary docker version hiccup and now break service resolution
(lookup docker: no such host). Back to the plain docker:dind service.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Change-Id: I5cf2d14482aaab2c3a943f5c46336c3015ae724e
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 97bebd3..498626e 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -23,12 +23,8 @@
 test-docker-image:
   image: docker:latest
   stage: test
-  variables:
-    FF_NETWORK_PER_BUILD: "true"
   services:
-    - name: docker:dind
-      alias: docker
-      command: ["--dns=127.0.0.11", "--dns=8.8.8.8"]
+    - docker:dind
   before_script:
     - apk update
     - apk add --no-cache bash
@@ -43,12 +39,8 @@
 build-docker-image:
   image: docker:latest
   stage: build
-  variables:
-    FF_NETWORK_PER_BUILD: "true"
   services:
-    - name: docker:dind
-      alias: docker
-      command: ["--dns=127.0.0.11", "--dns=8.8.8.8"]
+    - docker:dind
   rules:
     - if: $CI_COMMIT_TAG =~ /.+/
       variables:
@@ -81,12 +73,8 @@
 deploy-to-docker-hub:
   image: docker:latest
   stage: deploy
-  variables:
-    FF_NETWORK_PER_BUILD: "true"
   services:
-    - name: docker:dind
-      alias: docker
-      command: ["--dns=127.0.0.11", "--dns=8.8.8.8"]
+    - docker:dind
   rules:
     - if: $CI_COMMIT_TAG =~ /.+/
     - when: manual