Prevent scheduled task cancelation from emitting error logs

[jstnlef]

Description

When trying to cancel scheduled tasks with their corresponding CancelationSource, I noticed error logs were constantly being emitted. The root cause of this turned out to be that the inner Task.Delay ends up being the task that is canceled rather than the outer Task.run so it would always throw an exception. I'm fairly convinced that it isn't necessary to check since no caller could possibly have access to the running task to catch the cancelation exception anyway.

Purpose

This pull request is a:

• Bugfix (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 not work as expected)

Checklist

• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)

[CLAassistant]

All committers have signed the CLA.