Removing magic numbers from exceptions (#23997)

* Removing magic numbers from exceptions

* Running pre-commit

(cherry picked from commit 375673a)

airflow/exceptions.py

@@ -21,6 +21,7 @@
 """Exceptions used by Airflow"""
 import datetime
 import warnings
+from http import HTTPStatus
 from typing import Any, Dict, List, NamedTuple, Optional, Sized
 
 
@@ -31,19 +32,19 @@ class AirflowException(Exception):
     Each custom exception should be derived from this class.
     """
 
-    status_code = 500
+    status_code = HTTPStatus.INTERNAL_SERVER_ERROR
 
 
 class AirflowBadRequest(AirflowException):
     """Raise when the application or server cannot handle the request."""
 
-    status_code = 400
+    status_code = HTTPStatus.BAD_REQUEST
 
 
 class AirflowNotFoundException(AirflowException):
     """Raise when the requested object/resource is not available in the system."""
 
-    status_code = 404
+    status_code = HTTPStatus.NOT_FOUND
 
 
 class AirflowConfigException(AirflowException):