Recipe: Don't overwrite subclass-overridden recipe

Author: ndevenish

src/workflows/recipe/recipe.py

@@ -25,7 +25,7 @@ def __init__[KT: RecipeKey | str](self, recipe: dict[KT, Any] | str | None = Non
             self.recipe = self.deserialize(recipe)
         elif recipe:
             self.recipe = self._sanitize(recipe)
-        else:
+        elif not hasattr(self, "recipe"):
             self.recipe = {}
 
     def deserialize(self, data: str) -> RawRecipe: