Feed cloudops-infra env into `tests/test_init.py`

[ahal]

I recently added a test that runs the docker.d/init.sh script. The problem is that it relies on a ton of environment variables that are populated from cloudops-infra. To get around this, I basically just manually created a giant context dict containing dummy values for everything.

Ben had the idea of trying to fetch these directly (would need a Github API token) and using the actual variables fetched from the cloudops-infra repo. Not only would this make manual maintenance less of a burden, but it would turn test_init.sh into an integration test that covers parts of the deploy pipeline with cloudops-infra as well.

Note that the values come from SOPS, so we'd obviously still need dummy values for the keys.. But these could be autogenerated for any keys we detect.