style(firebase_auth): remove outdated comment

- Remove unnecessary comment block in FirebaseAuthenticator constructor
- Retain important inline comment about HttpClient usage

Author: fulleni

lib/src/services/firebase_authenticator.dart

@@ -23,7 +23,6 @@ class FirebaseAuthenticator implements IFirebaseAuthenticator {
   /// {@macro firebase_authenticator}
   /// Creates an instance of [FirebaseAuthenticator].
   FirebaseAuthenticator({required Logger log}) : _log = log {
-    // This internal HttpClient is used exclusively for the token exchange.
     // This internal HttpClient is used exclusively for the token exchange.
     // It does not have an auth interceptor, which is crucial to prevent
     // an infinite loop.