Deprecate docker registry

[soapy1]

Context

Conda-store was once able to build docker images and host them in it's own docker registry. The docker workflows for conda store have fallen into disrepair and is have not been used by anyone in some time. It would be nice to remove this feature to reduce cruft in the code base. If it becomes clear that it would be helpful to have this feature again, it should be re-implemented with a more modern approach.

Value and/or benefit

The goal of this is to remove cruft and simplify the conda-store app.

related to #941

[soapy1]

@peytondmurray do you have opinions about if this should go thru a proper deprecation cycle, or if it's ok to yank out? I'm not sure anyone is using it, but the feature does still seem to work when I tested in locally. I'd be ok with deprecating and removing over a few releases.

[peytondmurray]

@trallard @kcpevey @Adam-D-Lewis @krassowski Bringing this to your attention - any concerns about removing this iteration of the docker feature?

[Adam-D-Lewis]

I'm not aware of anyone using it, but could we at least document what seems to be going wrong at the moment? I wasn't aware that it no longer was working.

[soapy1]

@Adam-D-Lewis I believe the registry is working, but building docker images has been disabled https://github.com/conda-incubator/conda-store/blob/main/conda-store-server/conda_store_server/_internal/worker/build.py#L423, looks like for the past year. I think if conda-store isn't building docker images, there isn't really too much use for a registry.

[peytondmurray]

Looks like it never really went through a formal deprecation cycle anyway, it just got turned off. But it looks like it should have been generating warning messages about the feature not working...so maybe it's fine to remove at this point?