ci(travis): fix `opensuse` tests

nginx/ng/map.jinja

             'service': 'nginx',
             'webuser': 'nginx',
             'conf_file': '/etc/nginx/nginx.conf',
-            'server_available': '/etc/nginx/sites-available',
-            'server_enabled': '/etc/nginx/sites-enabled',
+            'server_available': '/etc/nginx/vhosts.d',
+            'server_enabled': '/etc/nginx/vhosts.d',
             'snippets_dir': '/etc/nginx/snippets',
             'server_use_symlink': False,
             'pid_file': '/run/nginx.pid',

test/integration/default/controls/config.rb

 when 'redhat', 'centos', 'fedora'
   server_available = '/etc/nginx/conf.d'
   server_enabled   = '/etc/nginx/conf.d'
+when 'opensuse'
+  server_available = '/etc/nginx/vhosts.d'
+  server_enabled   = '/etc/nginx/vhosts.d'
 end
 
 control 'Nginx configuration' do