### 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/GoogleCloudStorageClientSettings.java
return credential;
    }
    public String getHost() {
        return endpoint;
    }
    public String getProjectId() {
        return Strings.hasLength(projectId) ? projectId : (credential != null ? credential.getProjectId() : null);
    }
    public TimeValue getConnectTimeout() {
        return connectTimeout;
    }
    public TimeValue getReadTimeout() {
        return readTimeout;
    }
    public String getApplicationName() {
        return applicationName;
    }
    public URI getTokenUri() {
        return tokenUri;
    }
    @Nullable
    public Proxy getProxy() {
        return proxy;
    }
    public static Map<String, GoogleCloudStorageClientSettings> load(final Settings settings) {
        final Map<String, GoogleCloudStorageClientSettings> clients = new HashMap<>();
        for (final String clientName : settings.getGroups(PREFIX).keySet()) {
            clients.put(clientName, getClientSettings(settings, clientName));
        }
        if (clients.containsKey("default") == false) {