Cache Hook when initializing CloudFormationCreateStackSensor (#14638)

- `CloudFormationCreateStackSensor` created `AWSCloudFormationHook` in its init method
- This commit delays creation of hook until it is needed

airflow/providers/amazon/aws/sensors/cloud_formation.py

@@ -18,6 +18,11 @@
 """This module contains sensors for AWS CloudFormation."""
 from typing import Optional
 
+try:
+    from functools import cached_property
+except ImportError:
+    from cached_property import cached_property
+
 from airflow.providers.amazon.aws.hooks.cloud_formation import AWSCloudFormationHook
 from airflow.sensors.base import BaseSensorOperator
 from airflow.utils.decorators import apply_defaults
@@ -43,7 +48,8 @@ class CloudFormationCreateStackSensor(BaseSensorOperator):
     def __init__(self, *, stack_name, aws_conn_id='aws_default', region_name=None, **kwargs):
         super().__init__(**kwargs)
         self.stack_name = stack_name
-        self.hook = AWSCloudFormationHook(aws_conn_id=aws_conn_id, region_name=region_name)
+        self.aws_conn_id = aws_conn_id
+        self.region_name = region_name
 
     def poke(self, context):
         stack_status = self.hook.get_stack_status(self.stack_name)
@@ -53,6 +59,11 @@ def poke(self, context):
             return False
         raise ValueError(f'Stack {self.stack_name} in bad state: {stack_status}')
 
+    @cached_property
+    def hook(self) -> AWSCloudFormationHook:
+        """Create and return an AWSCloudFormationHook"""
+        return AWSCloudFormationHook(aws_conn_id=self.aws_conn_id, region_name=self.region_name)
+
 
 class CloudFormationDeleteStackSensor(BaseSensorOperator):
     """
@@ -83,20 +94,16 @@ def __init__(
         self.aws_conn_id = aws_conn_id
         self.region_name = region_name
         self.stack_name = stack_name
-        self.hook: Optional[AWSCloudFormationHook] = None
 
     def poke(self, context):
-        stack_status = self.get_hook().get_stack_status(self.stack_name)
+        stack_status = self.hook.get_stack_status(self.stack_name)
         if stack_status in ('DELETE_COMPLETE', None):
             return True
         if stack_status == 'DELETE_IN_PROGRESS':
             return False
         raise ValueError(f'Stack {self.stack_name} in bad state: {stack_status}')
 
-    def get_hook(self) -> AWSCloudFormationHook:
+    @cached_property
+    def hook(self) -> AWSCloudFormationHook:
         """Create and return an AWSCloudFormationHook"""
-        if self.hook:
-            return self.hook
-
-        self.hook = AWSCloudFormationHook(aws_conn_id=self.aws_conn_id, region_name=self.region_name)
-        return self.hook
+        return AWSCloudFormationHook(aws_conn_id=self.aws_conn_id, region_name=self.region_name)