harden nginx

From @maverickquant:

---

Other General Nginx Security concerns and recommendations:

* [ ] ~~Disable Unwanted HTTP Methods in Nginx~~

```
if ($request_method !~ ^(GET|HEAD|POST)$) {
return 444;
}
```

* [ ] Disable weak cipher suites-Enable Strong TLS Ciphers

Set your cipher strength to something secure, yet compatible. Add following under server block in ssl.conf file:

```
ssl_ciphers "EECDH+ECDSA+AESGCM EECDH+aRSA+AESGCM EECDH+ECDSA+SHA384 EECDH+ECDSA+SH
```

Not sure if there is a GSA standard for this ciphers-.Will confirm and let you know.

* [x] Avoid self-signed certs especially in prod.
* [ ] Remove Unnecessary Modules in Nginx -if any
* [ ] Setup Monitor Logs for Nginx
* [ ] ~~proxy_ssl_verify: on :: ensure on:: Verifies the validity of certificates.~~
* [ ] Restrict Access by IP from Nginx.
* [ ] Limit Input Traffic via IPTables.
* [x] Disable server_tokens Directive in Nginx. The server_tokens directive tells Nginx to display its current version on error pages.

---

Crossed off items that I don't believe are applicable.

Start by reviewing the Terraform and Ansible deployment configuration, then locate the Nginx server block and ssl.conf referenced in the issue. Determine which unchecked security recommendations apply to this deployment and validate the selected changes. Done means the applicable hardening work is implemented and deployment checks pass.

Written by the indexing model from the issue text.