Allow use of `custom_gitlab_server_config` in Pages HTTP server

I'm using custom_gitlab_server_config to add custom nginx directives in order to redirect /.well-known LetEncrypt's request to a static directory on which I use certbot with a --webroot-path option to renew my GitLab certificates:

[...]
nginx['custom_gitlab_server_config'] = "location ^~ /.well-known {\n alias /var/www/letsencrypt/.well-known;\n}\n"
[...]
pages_nginx['custom_gitlab_server_config'] = "location ^~ /.well-known {\n alias /var/www/letsencrypt/.well-known;\n}\n"
[...]

This configuration works for the main nginx server, but it does not work with the pages nginx server.

Here is the patch I came up with which I'm currently using on my GitLab instance: jerome.auge/omnibus-gitlab@d4ee8b11