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/test/java/org/elasticsearch/xpack/security/cli/HttpCertificateCommandTests.java
final String esReadme = Files.readString(esReadmePath);
        final Path ymlPath = zipRoot.resolve("elasticsearch/sample-elasticsearch.yml");
        assertThat(ymlPath, isRegularFile());
        final String yml = Files.readString(ymlPath);
        
        verifyCertificationRequest(csr, certificateName, hostNames, ipAddresses);
        
        assertMatchingPair(getPublicKey(csr), privateKey);
        final String csrName = csrPath.getFileName().toString();
        final String crtName = csrName.substring(0, csrName.length() - 4) + ".crt";
        
        assertThat(esReadme, containsString(csrName));
        assertThat(esReadme, containsString(crtName));
        assertThat(esReadme, containsString(keyPath.getFileName().toString()));
        assertThat(esReadme, containsString(ymlPath.getFileName().toString()));
        if ("".equals(password) == false) {
            assertThat(esReadme, not(containsString(password)));
        }
        
        assertThat(yml, not(containsString(csrName)));
        assertThat(yml, containsString(crtName));
        assertThat(yml, containsString(keyPath.getFileName().toString()));
        if ("".equals(password) == false) {
            assertThat(yml, not(containsString(password)));
        }
        
        assertThat(zipRoot.resolve("ca"), not(pathExists()));
        
        verifyKibanaDirectory(
            zipRoot,