refactor: remove local ad platform type

- Remove case AdPlatformType.local from AdPlatformTypeL10n extension
- This change simplifies the ad platform type localization by removing the local option

Author: fulleni

lib/shared/extensions/ad_platform_type_l10n.dart

@@ -10,8 +10,6 @@ extension AdPlatformTypeL10n on AdPlatformType {
     switch (this) {
       case AdPlatformType.admob:
         return l10n.adPlatformTypeAdmob;
-      case AdPlatformType.local:
-        return l10n.adPlatformTypeLocal;
       case AdPlatformType.demo:
         throw UnimplementedError(
           'Demo ad platform type is not intended for dashboard usage, rather for mobile client, demo env specific usecase.',