Choosing Whether to Enable Retries in Firebase App Options

Hello,
I have learned that FCM automatically retries when a 503 response is received.
However, our service already handles retries for undelivered messages through scheduling, so we do not want to use the default retry strategy.
```
public static HttpRequestFactory newAuthorizedRequestFactory(
FirebaseApp app, @Nullable RetryConfig retryConfig) {
HttpTransport transport = app.getOptions().getHttpTransport();
return transport.createRequestFactory(new FirebaseRequestInitializer(app, retryConfig));
}
```
To disable this behavior, I attempted to use a method provided in the ApiClientUtils class.
However, after debugging the initialization process, I found that it is not possible to set a custom RetryConfig value.

I assume there is a valid reason for restricting the redefinition of RetryConfig.
For example, it may be to prevent retries for responses other than 5xx errors or to avoid excessive retry requests within a short period.

What I would like is the ability to **enable or disable the retry feature as needed.**
I will proceed with creating a PR for this.

Beginne damit, ApiClientUtils und die gezeigte newAuthorizedRequestFactory-Methode durch die Initialisierung von FirebaseApp zu verfolgen, wobei du dich darauf konzentrierst, wo RetryConfig festgelegt oder eingeschränkt wird. Ermittle die unterstützte Möglichkeit, Retries zu aktivieren oder zu deaktivieren, ohne das übrige Retry-Verhalten zu ändern, und überprüfe, dass beide konfigurierten Modi für FCM-Anfragen funktionieren.

Vom Indexierungsmodell aus dem Issue-Text verfasst.