Always set git proxy variables
This MR makes sure that the git config
proxy variables are set to the same value as the corresponding proxy environment variables.
This is necessary because in some edge cases git ignores the environment variables.
I'm still investigating why git ignores the environment variables sometimes, but since this is a very simple fix, I figured I'd make a quick MR.
I'll add some docs regarding executing the runner behind a proxy in another MR soon.
closes #1537
/cc @tmaczukin @ayufan