### 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
(key) -> new Setting<>(key, "DIRECT", s -> Proxy.Type.valueOf(s.toUpperCase(Locale.ROOT)), Setting.Property.NodeScope)
    );
    
    static final Setting.AffixSetting<String> PROXY_HOST_SETTING = Setting.affixKeySetting(
        PREFIX,
        "proxy.host",
        (key) -> Setting.simpleString(key, Setting.Property.NodeScope),
        () -> PROXY_TYPE_SETTING
    );
    
    static final Setting.AffixSetting<Integer> PROXY_PORT_SETTING = Setting.affixKeySetting(
        PREFIX,
        "proxy.port",
        (key) -> Setting.intSetting(key, 0, 0, 65535, Setting.Property.NodeScope),
        () -> PROXY_HOST_SETTING
    );
    
    private final ServiceAccountCredentials credential;
    
    private final String endpoint;
    
    private final String projectId;
    
    private final TimeValue connectTimeout;
    
    private final TimeValue readTimeout;
    
    private final String applicationName;
    
    private final URI tokenUri;