chore: remove duplicate test helper classes from api root directory (#25024)

api/child_class.py

-from tests.integration_tests.utils.parent_class import ParentClass
-
-
-class ChildClass(ParentClass):
-    """Test child class for module import helper tests"""
-
-    def __init__(self, name):
-        super().__init__(name)
-
-    def get_name(self):
-        return f"Child: {self.name}"

api/lazy_load_class.py

-from tests.integration_tests.utils.parent_class import ParentClass
-
-
-class LazyLoadChildClass(ParentClass):
-    """Test lazy load child class for module import helper tests"""
-
-    def __init__(self, name):
-        super().__init__(name)
-
-    def get_name(self):
-        return self.name