Use cloudsmith action 0.5.4 -> 0.6.10, new builder hosted by ghcr.io

[Nuru]

what

• Update builder image host from Docker Hub to ghcr.io (and use new builder)
• Update Cloudsmith action 0.5.4 -> 0.6.10
• Do not automatically run package builder workflow on push to main if nothing has changed but the workflow file
• Do not automatically run package builder workflow on PR if branch name starts with mass-update/

why

• When mass-updating packages, we hit Docker Hub rate limits, but ghcr.io is more permissive (and better performing on GitHub-hosted runners).
• Old Cloudsmith action ran in a Docker image, and we occasionally ran into issues with Docker-in-Docker. New action is just a Python executable, which works better, but requires us to pre-install Python, which we did in the new builders with Update build OSes, pre-install Python #4762.
• Usually, changes to the workflow file are not relevant to the package itself, but are maintenance issues such as updating the action version. Avoid all the waste and overhead of rebuilding packages when nothing substantive has changed.
• When updating a single package, allow the workflow to run, but provide a mechanism to update all the workflows without triggering runs, to avoid the massive unneeded workflow.

references

• Supersedes and closes Update Cloudsmith action #4724