Refactor to use TimeInterval.milliseconds

[gibachan]

Issue #, if available: closes #398

Description of changes: Refactor to use TimeInterval extension method.

Check points: (check or cross out if not relevant)

• [ ] Added new tests to cover change, if needed
• [ ] Build succeeds with all target using Swift Package Manager
• [x] All unit tests pass
• [ ] All integration tests pass
• [ ] Security oriented best practices and standards are followed (e.g. using input sanitization, principle of least privilege, etc)
• [ ] Documentation update for the change if required
• [ ] PR title conforms to conventional commit style
• [ ] If breaking change, documentation/changelog update with migration instructions

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

[atierian]

Thanks for opening this @gibachan. This looks like a pretty straightforward change that is needed. I'll have someone familiar with that area of the code base review it.

[gibachan]

Thank you for your support.