fix: Remove concurrency group from container-images-cd (#21541)

Remove concurrency group from container-images-cd

This can cause deploys to be skipped if another change is merged that doesn't trigger the
same deploys. There's no harm in running this job concurrently as the triggered deploys will
still be in concurrency groups

.github/workflows/container-images-cd.yml

@@ -15,8 +15,6 @@ on:
             - master
     workflow_dispatch:
 
-concurrency: ${{ github.workflow }} # ensure only one of this runs at a time
-
 jobs:
     posthog_build:
         name: Build and push PostHog