Refresh cgit asynchronously

[FrostyX]

When upgrading copr-dist-git from F39 to F41, the playbooks got "stuck" on running /usr/bin/copr-dist-git-refresh-cgit, warning us that it can take up to an hour to finish.

This is would be annoying in any circumstance but during an outage, while the previous copr-dist-git instance is down, it is not feasible to wait an hour for this task to finish. As a workaround, we had to temporarily put an exit 0 at the start of the script so that playbooks go through quicker.

Also, this caught me as a surprise, as this doesn't happen on copr-distgit-dev because we don't have as much data there