feat: Add integration tests for services with specific customizations

[dayaffe]

Describe the feature

We should have integration tests for services with specific customizations. E.g., AWSGlacier has specific customizations such as the Sha256Middleware.

Use Case

For ensuring code changes don't break services with customizations.

Proposed Solution

No response

Other Information

Other than S3 which we already have tests for, there're Glacier, Route53, APIGateway, and MachineLearning.
Related ticket: #1027

Note:

• APIGateway's customization that adds a header to request is straightforward and already is in correct order.
• MachineLearning's customization requires machine learning model setup; revisit later if needed.

Acknowledgements

• I may be able to implement this feature request
• This feature might incur a breaking change