Before GrowthExperiments-CommunityConfiguration was a thing, Growth features were configured server-side, in the operations/mediawiki-config repository. Now that we use on-wiki config for it, the server-side config is not in use (and potentially, out of date).
Initially, in-repo config was kept, to act as a fallback for cases when the on-wiki store fails. Since community configuration is with us for some time, we would likely notice if it had bugs.
All newly deployed wikis (as part of Growth-Deployments) don't have server-side config at all.
After considering the current state of community configuration, and after discussion with @Tgr, I think we're safe now to remove config that's now on-wiki from operatons/mediawiki-config.