Fix trailing space in `nginx_vhost.conf.master` at `server_name` property

Summary

Sometimes a trailing space in the server_name property causes nginx to listen to the website on all hosts, causing conflicts.

Steps to reproduce

1. Create website without alias (www., or *.)

Correct behaviour

If no website alias is specified, do not insert a trailing space.

Environment

Server OS + version: Ubuntu 24.04 ISPConfig version: 3.2.12p1

Software version of the related software: nginx/1.24.0

Proposed fix

Replace

server_name <tmpl_var name='domain'> <tmpl_var name='alias'>;

with

server_name <tmpl_var name='domain'><tmpl_if name='alias'> <tmpl_var name='alias'></tmpl_if>;

in nginx_vhost.conf.master template.