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/AutoConfigureNodeTests.java
"http.host: [_site_]",
            "xpack.security.enabled: true",
            "xpack.security.enrollment.enabled: true",
            "xpack.security.http.ssl.enabled: true",
            "some.extra.added.setting: value",
            "xpack.security.http.ssl.keystore.path: /path/to/the/file",
            "xpack.security.transport.ssl.keystore.path: /path/to/the/file",
            "xpack.security.transport.ssl.truststore.path: /path/to/the/file",
            "",
            AutoConfigureNode.AUTO_CONFIGURATION_END_MARKER
        );
        assertEquals(file1, removePreviousAutoconfiguration(file2));
    }
    public void testGeneratedHTTPCertificateSANs() throws Exception {
        
        Path tempDir = createTempDir();
        try {
            Files.createDirectory(tempDir.resolve("config"));
            
            Files.write(tempDir.resolve("config").resolve("elasticsearch.yml"), List.of(), CREATE_NEW);
            X509Certificate httpCertificate = runAutoConfigAndReturnHTTPCertificate(tempDir, Settings.EMPTY);
            assertThat(checkGeneralNameSan(httpCertificate, "dummy.test.hostname", GeneralName.dNSName), is(true));
            assertThat(checkGeneralNameSan(httpCertificate, "localhost", GeneralName.dNSName), is(true));
        } finally {
            deleteDirectory(tempDir);
        }
        
        tempDir = createTempDir();
        try {
            Files.createDirectory(tempDir.resolve("config"));