We generate certificates that are intended to be used for server authentication in a couple of places:

- `bin/elasticsearch-certutil http` command  ( See `CertGenUtils.generateSignedCertificate` in `HttpCertificateCommand` )
- TLS auto-configuraion for node startup ( see [`AutoConfigureNode`](https://github.com/elastic/elasticsearch/blob/814f7f9f52cb8c05db6465b9bfc818ea5d76c575/x-pack/plugin/security/cli/src/main/java/org/elasticsearch/xpack/security/cli/AutoConfigureNode.java#L454) )

In these cases we know that the certificate is meant to be used for server authentication, so we can set Extended Key Usage extension to `1.3.6.1.5.5.7.3.1`
x-pack/plugin/security/cli/src/main/java/org/elasticsearch/xpack/security/cli/AutoConfigureNode.java
);
                final KeyPair httpCaKeyPair = CertGenUtils.generateKeyPair(HTTP_CA_KEY_SIZE);
                httpCaKey = httpCaKeyPair.getPrivate();
                
                httpCaCert = CertGenUtils.generateSignedCertificate(
                    caPrincipal,
                    null,
                    httpCaKeyPair,
                    null,
                    null,
                    true,
                    HTTP_CA_CERTIFICATE_DAYS,
                    SIGNATURE_ALGORITHM
                );
            } catch (Throwable t) {
                try {
                    deleteDirectory(tempGeneratedTlsCertsDir);
                } catch (Exception ex) {
                    t.addSuppressed(ex);
                }
                
                
                throw t;
            }
        }
        try {
            final KeyPair httpKeyPair = CertGenUtils.generateKeyPair(HTTP_KEY_SIZE);
            httpKey = httpKeyPair.getPrivate();
            
            httpCert = CertGenUtils.generateSignedCertificate(