Make magician's git controller not require a token

[melinath]

In a number of cases, we're only passing a github token into a particular step of the CI pipeline because the object that controls interacting with the git repository requires one (even for publicly readable repositories). We should remove that requirement.

[melinath]

There might already not be a requirement - if an empty token works here then we can just stop passing in a token in the command. We should be able to stop providing the env var at the same time.

[NA2047]

@melinath

[melinath]

@NA2047 are you still working on this?