remove None from typehints for ias_flavour in imported ias

gso/workflows/l3_core_service/ias/create_imported_ias.py

@@ -27,8 +27,8 @@ def initial_input_form_generator() -> FormGenerator:
     initial_user_input = yield from initial_generator
 
     # Additional IAS step
-    class IASExtraForm(FormPage):  # TODO: Think about the order of this form when user is filling it
-        ias_flavor: IASFlavor | None = IASFlavor.IAS_PS_OPT_OUT
+    class IASExtraForm(FormPage):
+        ias_flavor: IASFlavor = IASFlavor.IAS_PS_OPT_OUT
 
     ias_extra = yield IASExtraForm
     return initial_user_input | ias_extra.model_dump()