Changed ruby version to 2.7.x to match upstream.
Added a gem config for gitlab-pg_query as it tries to download a source
tarball during the build process.
Also removed a patch for gitaly that has become obsolete by upstream fix
[here](de04077c25).
- gitlab-shell no longer requires ruby for anything else than the
install script, so the bundlerEnv stuff could be dropped
- gitlab-shell and gitlab-workhorse now report their versions
correctly
GitLab recently restructured their repos; whereas previously they had
one gitlab-ce and one gitlab-ee repo, they're now one and the
same. All proprietary components are put into the ee subdirectory -
removing it gives us the foss / community version of GitLab. For more
info, see
https://about.gitlab.com/2019/02/21/merging-ce-and-ee-codebases/
This gives us the opportunity to simplify things quite a bit, since we
don't have to keep track of two separate versions of either the base
data or rubyEnv.
