swap pa11y runner (DataDog#21651)

Author: stanleegoodspeed

.gitlab-ci.yml

@@ -463,7 +463,7 @@ link_checks:on-schedule:
 # template for what runs in pa11y to avoid duplication
 .pa11y_live_template: &pa11y_live_template
  image: 486234852809.dkr.ecr.us-east-1.amazonaws.com/ci/websites-images:pa11y-25121683
- tags: ["runner:docker"]
+ tags: ["arch:amd64"]
  stage: post-deploy
  cache: []
  variables: