Fix bugs in MWAA verify_env: S3 client reference and missing json importFix/mwaa verify env

[eason1128]

Summary

This PR fixes two bugs in the MWAA verify_env tool:

1. Fixed incorrect S3 client reference in airflow_verifier.py: Changed s3 to self.s3 in the delete_file_from_dags_folder method call (line 286). The previous code would cause a NameError when users chose to delete the test DAG after running the full DAG run test.

2. Added missing json import in utils.py: The module uses JSON functionality but was missing the import statement.

Changes

• airflow_verifier.py:286 - Fixed S3 client parameter from s3 to self.s3
• utils.py:20 - Added import json statement

Testing

• Verified that the S3 client reference now correctly points to the instance variable
• Confirmed that the json module is properly imported for JSON operations

Impact

These fixes ensure that:

• The test DAG deletion feature works correctly without throwing NameError
• The utils module has all required imports for its functionality

[ankon]

Also ran into the missing import:

Traceback (most recent call last):
  File ".../aws-support-tools/MWAA/verify_env/verify_env.py", line 99, in <module>
    iam_verifier.check_iam_permissions()
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^
  File ".../aws-support-tools/MWAA/verify_env/iam_verifier.py", line 51, in check_iam_permissions
    policy_list.extend(get_inline_policies(self.iam, self.env['ExecutionRoleArn'].split("/")[-1]))
                       ~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File ".../aws-support-tools/MWAA/verify_env/utils.py", line 88, in get_inline_policies
    json.dumps(iam_client.get_role_policy(RoleName=role_arn, PolicyName=policy).get("PolicyDocument", ))
    ^^^^
NameError: name 'json' is not defined. Did you forget to import 'json'?