refactor: simplify configuration handling for CMS URL

- Removed CmsServerBaseUrl utility class and updated references to directly access GwUrl from configuration.
- Adjusted frontoffice-deployment.yaml to remove CmsInternalBaseUrl environment variable.
- Updated appsettings for staging and main environments to reflect the correct CMS service URLs.
- Ensured consistent handling of GwUrl in TokenNotificationService and AddGrpcServices methods.

src/FrontOffice.Main/Utilities/TokenNotificationService.cs

@@ -69,7 +69,7 @@ public class TokenNotificationService : IAsyncDisposable
                 return;
             }
 
-            var gwUrl = CmsServerBaseUrl.Resolve(_configuration) ?? "https://localhost:5002";
+            var gwUrl = _configuration["GwUrl"]?.TrimEnd('/') ?? "https://localhost:5002";
             var hubPath = _configuration["SignalR:HubPath"] ?? "/hubs/token-relay";
             var hubUrl = $"{gwUrl}{hubPath}";