fix: fail-fast CI, write Docker apt source directly, fix arch mapping

Three changes:
1. CI: add set -e and fail-fast: true to stop on first molecule failure
   instead of continuing (all pairs fail for same reason anyway)
2. Docker APT repo: use copy module to write sources.list directly
   instead of apt_repository module which wasn't picking up the repo
3. Fix arch mapping: ansible_facts returns x86_64, Docker repo needs amd64

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Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

.gitea/workflows/ci.yml

@@ -30,6 +30,7 @@ jobs:
     needs: quality
     runs-on: docker
     strategy:
+      fail-fast: true
       matrix:
         runner-index: [0, 1, 2]
     steps:
@@ -44,6 +45,7 @@ jobs:
           echo "TEST_PAIRS=$PAIRS" >> $GITHUB_ENV
       - name: Run molecule tests
         run: |
+          set -e
           . .venv/bin/activate
           export DOCKER_HOST="unix:///run/user/$(id -u)/docker.sock"
           export ANSIBLE_INJECT_INVOCATION=1