Use template engine for system test configs

Use jinja2 engine for configuring named.conf.in files in system tests. This should allow us to get rid of many setup.sh files which only do copy_setports.

This will also allow us to use more complex template options to include/exclude entire blocks conditionally, rather than using multiple config files named1.conf.in, named2.conf.in...

While this adds a new dependency (jinja2) for system tests, I think this one is worth it.

Related #3810