Fix async waiting in DynamoDBRetryPolicy.

[teo-tsirpanis]

Description

This PR updates DynamoDBRetryPolicy to override the WaitBeforeRetryAsync method in order to use the updated retry logic for async retries in addition to sync ones.

Motivation and Context

Noticed as part of a larger clean-up effort, and split into its own branch.

Testing

N/A

Screenshots (if appropriate)

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• My code follows the code style of this project
• My change requires a change to the documentation
• I have updated the documentation accordingly
• I have read the README document
• I have added tests to cover my changes
• All new and existing tests passed

License

• I confirm that this pull request can be released under the Apache 2 license

[teo-tsirpanis]

Turns out that without this PR, we will not block the thread, but will fall back to the default and non-DynamoDB-specific retry logic. Updated PR title and description.

[muhammad-othman]

Running internal dry run DRY_RUN-8a5da552-276c-4742-9f14-867dc629ab26.

[muhammad-othman]

Added dev config and internal dry run succeeded DRY_RUN-8a5da552-276c-4742-9f14-867dc629ab26.