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 String msg = String.format(
                Locale.ROOT,
                "Skipping security auto configuration because the configuration file [%s] is missing or is not a regular file",
                ymlPath
            );
            notifyOfFailure(inEnrollmentMode, terminal, Terminal.Verbosity.NORMAL, ExitCodes.CONFIG, msg);
        }
        
        if (false == Files.isReadable(ymlPath)) {
            final String msg = String.format(
                Locale.ROOT,
                "Skipping security auto configuration because the current user does not have permission to read "
                    + " configuration file [%s]",
                ymlPath
            );
            notifyOfFailure(inEnrollmentMode, terminal, Terminal.Verbosity.NORMAL, ExitCodes.NOOP, msg);
        }
        final Path keystorePath = KeyStoreWrapper.keystorePath(env.configFile());
        
        if (Files.exists(keystorePath)
            && (false == Files.isRegularFile(keystorePath, LinkOption.NOFOLLOW_LINKS) || false == Files.isReadable(keystorePath))) {
            final String msg = String.format(
                Locale.ROOT,
                "Skipping security auto configuration because the node keystore file [%s] is not a readable regular file",
                keystorePath
            );
            notifyOfFailure(inEnrollmentMode, terminal, Terminal.Verbosity.NORMAL, ExitCodes.NOOP, msg);
        }
        if (inReconfigureMode) {
            if (false == inEnrollmentMode) {