Move git version detection to gitaly from the rails application for usage ping data
Related to https://gitlab.com/charts/gitlab/issues/530
TLDR: For usage ping data, rails application needs to know the version of git available. It is done by Gitlab::Git.version, which essentially uses git binary to find out the version.
In CNG environment, unicorn nodes will not have git binary in them, only gitaly will do. So, rails application should be talking with Gitaly to find out that information, ideally.