dev/ci: proc Go checks on sg.config.yaml

Created by: bobheadxi

Resolves https://sourcegraph.slack.com/archives/C01N83PS4TU/p1654847045848989 , where a change to sg.config.yaml did not proc the generate check, since we generate some docs from it (sg reference). It's a bit heavy-handed, but we don't change sg.config.yaml that often and this might be useful in the future as we move testing into a sg test command as well.

Test plan

n/a