### Elasticsearch Version

8.x (any version where we have added support for proxies with a GCS repo)

### Installed Plugins

_No response_

### Java Version

_bundled_

### OS Version

N/A

### Problem Description

When configuring a GCS repository with HTTP proxy settings ([doc](https://www.elastic.co/guide/en/elasticsearch/reference/8.0/repository-gcs.html#repository-gcs-client)), we do not pass along the proxy settings to other `HttpTransportOptions` instances that we create. This can lead to timeout errors when the GCS Client tries to get a token, with the following error message:
```
Error getting access token for service account: Connect timed out, iss: ...
```

The workaround is to set the HTTP proxy settings on the JVM level rather than when defining the GCS repository, using `java.net.useSystemProxies` or `http.proxyHost`/`http.proxyPort`.

### Steps to Reproduce

[Setting up a GCS repository](https://www.elastic.co/guide/en/elasticsearch/reference/8.0/repository-gcs.html) with HTTP proxy settings (while every other non-proxied GCP call is blocked) could lead to this issue.

### Logs (if relevant)

_No response_
modules/repository-gcs/src/main/java/org/elasticsearch/repositories/gcs/GoogleCloudStorageService.java
*
     * @param gcsClientSettings client settings to use, including secure settings
     * @param stats the stats collector to use by the underlying SDK
     * @return a new client storage instance that can be used to manage objects
     *         (blobs)
     */
    private Storage createClient(GoogleCloudStorageClientSettings gcsClientSettings, GoogleCloudStorageOperationsStats stats)
        throws IOException {
        final HttpTransport httpTransport = SocketAccess.doPrivilegedIOException(() -> {
            final NetHttpTransport.Builder builder = new NetHttpTransport.Builder();
            
            
            
            
            final KeyStore certTrustStore = SecurityUtils.getJavaKeyStore();
            try (InputStream keyStoreStream = GoogleUtils.class.getResourceAsStream("google.jks")) {
                SecurityUtils.loadKeyStore(certTrustStore, keyStoreStream, "notasecret");
            }
            builder.trustCertificates(certTrustStore);
            Proxy proxy = gcsClientSettings.getProxy();
            if (proxy != null) {
                builder.setProxy(proxy);
                notifyProxyIsSet(proxy);
            }
            return builder.build();
        });
        final GoogleCloudStorageHttpStatsCollector httpStatsCollector = new GoogleCloudStorageHttpStatsCollector(stats);
        final HttpTransportOptions httpTransportOptions = new HttpTransportOptions(
            HttpTransportOptions.newBuilder()
                .setConnectTimeout(toTimeout(gcsClientSettings.getConnectTimeout()))