Coverage parsing improvements

[Code quality tools](https://github.com/MicrosoftPremier/VstsExtensions/blob/master/BuildQualityChecks/en-US/changeNotes.md) that check coverage may have diverged from our ability to use them.

1. Did the tools diverge from usefulness?
2. If so, consider a replacement like parsing the cobertura XML outputs. The code coverage outputs aren't as likely to change.