ensure-docker: remove amd64 architecture pin

Just let this install the repo for whatever architecture we're running
on.

Change-Id: Ifdff9b731db5d5ab93dd7da6f7d8a311b3162113

roles/ensure-docker/vars/debian.yaml

@@ -66,7 +66,7 @@ _docker_keys:
       -----END PGP PUBLIC KEY BLOCK-----
 
 _docker_repos:
-  - repo: "deb [arch=amd64] {{ docker_mirror_base_url }} {{ ansible_lsb.codename }} {{ docker_update_channel }}"
+  - repo: "deb {{ docker_mirror_base_url }} {{ ansible_lsb.codename }} {{ docker_update_channel }}"
 
 _docker_distro_packages:
   - docker.io

zuul-tests.d/container-roles-jobs.yaml

@@ -62,6 +62,24 @@
         - name: ubuntu-xenial
           label: ubuntu-xenial
 
+- job:
+    name: zuul-jobs-test-ensure-docker-ubuntu-bionic-arm64
+    description: Tests ensure-docker role on ubuntu-bionic-arm64
+    parent: zuul-jobs-test-ensure-docker
+    nodeset:
+      nodes:
+        - name: ubuntu-bionic-arm64
+          label: ubuntu-bionic-arm64
+
+- job:
+    name: zuul-jobs-test-ensure-docker-ubuntu-focal-arm64
+    description: Tests ensure-docker role on ubuntu-focal-arm64
+    parent: zuul-jobs-test-ensure-docker
+    nodeset:
+      nodes:
+        - name: ubuntu-focal-arm64
+          label: ubuntu-focal-arm64
+
 - job:
     name: zuul-jobs-test-build-docker-image-release
     description: |
@@ -390,6 +408,8 @@
         - zuul-jobs-test-ensure-docker-fedora-31
         - zuul-jobs-test-ensure-docker-ubuntu-bionic
         - zuul-jobs-test-ensure-docker-ubuntu-xenial
+        - zuul-jobs-test-ensure-docker-ubuntu-bionic-arm64
+        - zuul-jobs-test-ensure-docker-ubuntu-focal-arm64
         - zuul-jobs-test-build-docker-image-release
         - zuul-jobs-test-build-docker-image-release-multiarch
         - zuul-jobs-test-registry-docker