Userland: Prefer _string over _short_string

As `_string` can't fail anymore (since 3434412), there are no real
benefits to use the short variant in most cases.

Userland/DevTools/HackStudio/Debugger/RegistersModel.cpp

@@ -92,7 +92,7 @@ ErrorOr<String> RegistersModel::column_name(int column) const
     case Column::Register:
         return "Register"_string;
     case Column::Value:
-        return "Value"_short_string;
+        return "Value"_string;
     default:
         VERIFY_NOT_REACHED();
     }