FIRApp.configure is still causing Slow Launches on 12.3.0

### Description

I am aware that a fix was made for #14619 in version 12.2.0. However I am still experiencing several 'Slow Launches' when executing [FIRApp configure] on a simulator or device when running 12.3.0 on iOS 26.

This is an app with Analytics, Crashlytics and RemoteConfig installed manually via the zip files.

Please see screenshots of the stack traces below:

### Reproducing the issue

Run app with Analytics, Crashlytics and RemoteConfig installed and execute [FIRApp configure] in launch method.

### Firebase SDK Version

12.3.0

### Xcode Version

26.0

### Installation Method

Zip

### Firebase Product(s)

Analytics, Crashlytics, Remote Config

### Targeted Platforms

iOS

### Relevant Log Output

```shell
12.3.0 - [FirebaseSessions][I-SES000000] Version 12.3.0. Expecting subscriptions from: [Crashlytics]
12.3.0 - [FirebaseAnalytics][I-ACS023007] Analytics v.12.3.0 started
```

### If using Swift Package Manager, the project's Package.resolved

Expand Package.resolved snippet

```json

Replace this line with the contents of your Package.resolved.

```

### If using CocoaPods, the project's Podfile.lock

Expand Podfile.lock snippet

```yml

Replace this line with the contents of your Podfile.lock!

```