GitLab 11.5.1 dropped the dependency to posix_spawn, which is broken on
32bit. (See https://gitlab.com/gitlab-org/gitlab-ce/issues/53525)
The only part missing is decreasing virtualisation.memorySize to
something that a 32 bit qemu still executes.
The maximum seems to be 2047, and tests passed with that value for me.
The nixos test is a bit misleading, as the given nginx configuration
would always cause gitlab to redirect to localhost, which is clearly not
what you want in a production setup.
Instead we now enable services.nginx.recommendedProxySettings,
curl against http://gitlab, and assure we get redirected to that same
hostname, too.
