Edit file /home/gitlab/gitlab/config/unicorn.rb
Find line listen "#{app_dir}/tmp/sockets/gitlab.socket"
and comment it.
Uncomment line listen "127.0.0.1:8080"
sudo a2enmod proxy
sudo a2enmod proxy_balancer
sudo a2enmod proxy_http
sudo a2enmod rewrite
In general you don't need the passenger when you are using unicorn. You just need a proxy and a workaround for try files:
(See https://gitlab.com/gitlab-org/gitlab-recipes/tree/master/web-server/apache)