AzureDevOpsDsc: Enable integration tests

[johlju]

Pull Request (PR) description

• Enabled integration tests against https://dev.azure.com/azuredevopsdsc/ (see comment https://github.com/dsccommunity/AzureDevOpsDsc/issues/9#issuecomment-766375424 for more information).

This Pull Request (PR) fixes the following issues

Partly issue #9 (but does not fix)

Task list

• [x] Added an entry to the change log under the Unreleased section of the file CHANGELOG.md. Entry should say what was changed and how that affects users (if applicable), and reference the issue being resolved (if applicable).
• [ ] Resource documentation updated in the resource's README.md.
• [ ] Resource parameter descriptions updated in schema.mof.
• [ ] Comment-based help updated, including parameter descriptions.
• [ ] Localization strings updated.
• [ ] Examples updated.
• [ ] Unit tests updated. See DSC Community Testing Guidelines.
• [x] Integration tests updated (where possible). See DSC Community Testing Guidelines.
• [x] Code changes adheres to DSC Community Style Guidelines.

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This change is 

[johlju]

@SphenicPaul can you sign off on this so I can merge?

[johlju]

@SphenicPaul this is blocked by issue https://github.com/dsccommunity/AzureDevOpsDsc/issues/25. Do you have time to look at it? No hurry.

[johlju]

@SphenicPaul The test passed after kicking off the tests again, so lets review and merge this and we can track the problem in issue #25