Remove the use of the legacy signer

[sugmanue]

Motivation and Context

Removes the use of the legacy SigV4 signer in favor using the new HttpSigner interface for the following services

• RDS
• DocDB
• Neptune

For these services the SDK will add a pre-signed URL for some operations if a special param is used (DestinationRegion) to support cross-region operations. This pre-signed URL is added using an interceptor.

Modifications

The RdsPresignInterceptor for those services was changed to remove the use of the legacy SigV4 signer. Instead now we make use of the selected auth-scheme and the signer from its auth option which is configured to create the pre-signed URL.

Testing

All the existing tests were adapted for these changes. Additionally the tests were parametrized and additional ones were added to cover all the cases.

Screenshots (if appropriate)

Types of changes

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)

Checklist

• [ ] I have read the CONTRIBUTING document
• [ ] Local run of mvn install succeeds
• [ ] My code follows the code style of this project
• [ ] My change requires a change to the Javadoc documentation
• [ ] I have updated the Javadoc documentation accordingly
• [ ] I have added tests to cover my changes
• [ ] All new and existing tests passed
• [ ] I have added a changelog entry. Adding a new entry must be accomplished by running the scripts/new-change script and following the instructions. Commit the new file created by the script in .changes/next-release with your changes.
• [ ] My change is to implement 1.11 parity feature and I have updated LaunchChangelog

License

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