add aarch64 build job

Since we support the alternative name aarch64 for arm64 we should also
provide an optional build job for it in the template.

The build-ah-engine will per default only build amd64 and arm64

gitlab-ci-template.yml

@@ -48,6 +48,15 @@ container-build-arm64:
   rules:
     - if: '$CI_CONTAINER_BUILD_ARCHS =~ /:?arm64:?/ && $CI_PIPELINE_SOURCE != "merge_request_event"'
 
+container-build-aarch64:
+  extends: .container-build
+  variables:
+    CI_REGISTRY_IMAGE_ARCH: aarch64
+  tags:
+    - aaarch64
+  rules:
+    - if: '$CI_CONTAINER_BUILD_ARCHS =~ /:?aarch64:?/ && $CI_PIPELINE_SOURCE != "merge_request_event"'
+
 container-tagging:
   stage: tag
   inherit: