Use jinja2 templates in rpzrecurse test

Use jinja2 templates in rpzrecurse test

- Change ns2 header into jinja2 template.
- Keep the various ns2 config files as non-templates, same for the
  named.default.conf to be consistent.
- Symlink the ns2/named.default.conf as a jinja2 template to pick a
  starting config. It is rendered as a template to avoid an error when
  the test would overwrite a git-tracked file.
- Use jinja2 templates for the ns3 files, keep named1.conf around
  because it's needed later in the test to restore the config. Symlink
  it to `ns3/named.conf.j2` to select a default config.