Revert "Enable Native Python Types for Jinja2"

This reverts commit 3387035400ab7cc2f588fb096cfac446f2b25d10.

Enabling `jinja2_native` does help with the issue it is trying to
address - #151 (Github Pull Request), but it introduces a regression
when generating templates.

An example is
`roles/matrix-nginx-proxy/templates/nginx/conf.d/matrix-riot-web.conf.j2`,
which yields a strange resulting value of:

```
location /.well-known/acme-challenge {
    resolver 127.0.0.11 valid=5s;
    set $backend "matrix-certbot:8080";
    proxy_pass http://$backend;

    resolver 127.0.0.11 valid=5s;
    set $backend "matrix-certbot:8080";
    proxy_pass http://$backend;
}
```

For whatever reason (still to be investigated), the `if` block's
contents seem to have been outputted twice.

Reverting until this is resolved.
Until then, #151 would rely on the workaround and not on `jinja2_native`.

ansible.cfg

@@ -1,4 +1,2 @@
 [defaults]
 retry_files_enabled = False
-# jinja2_native helps with problems like https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/151
-jinja2_native = True