fix: Delete early exit check for unsigned chunk

[sichanyoo]

Issue \

https://github.com/awslabs/aws-sdk-swift/issues/1660

Description of changes

Refer to comments on GH diff for details

Scope

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

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[dayaffe]

please fix the github warnings!