Run the docker image size inside CircleCI instead of github actions

[lukasholzer]

Currently the GitHub actions for checking the image size are building the docker image again so we are building the image twice (waste of resources) furthermore does it take way longer than the circleci building.

So just run the manifest check on circleci (maybe build a orb for it and sync with @netlify/infrastructure-pod-release-eng about that.

https://github.com/netlify/whalescale/blob/main/index.js#L23-L36