Omnibus ships with two copies of the git binary

Two identical copies here:

1. /opt/gitlab/embedded/bin/git
2. /opt/gitlab/embedded/libexec/git-core/git

This also goes for git-upload-pack.

This caused confusion in production because we started patching /opt/gitlab/embedded/bin/git, but it wasn't enough.

I assume the first is just copied from the second? Can we just use a symlink instead?

/cc: @twk3