Add a project actor to non_public_artifacts feature flag

What does this MR do and why?

Main issue: #393891 (closed)

For the more gradual rollout (issue) of non_public_artifacts feature flag, which is disabled by default, we have to add a project actor to this feature flag.

Having the project actor involved would enhance flexibility throughout the rollout process.

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

MR acceptance checklist

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