VMNetworkAdapter: Fix Get- failing for a ManagementOS adapter

[jberezanski]

Pull Request (PR) description

The Get-NetworkInformation function does not work for a ManagementOS
adapter and should not be called in that code path in Get-TargetResource.

This Pull Request (PR) fixes the following issues

None

Task list

• 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 added/updated in README.md.
• Resource parameter descriptions added/updated in README.md, schema.mof
  and comment-based help.
• Comment-based help added/updated.
• Localization strings added/updated in all localization files as appropriate.
• Examples appropriately added/updated.
• Unit tests added/updated. See DSC Community Testing Guidelines.
• Integration tests added/updated (where possible). See DSC Community Testing Guidelines.
• New/changed code adheres to DSC Community Style Guidelines.

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This change is 

[jberezanski]

It seems the unit tests are completely broken, possibly due to breaking changes in Pester 5.x. And even if they were correct syntacticaly, most of the tests of this resource contain logic flaws.
I can attempt to fix this, but it will take some time.

[johlju]

We have renamed the resource, removing 'x', so please rebase this PR.

[jberezanski]

I never noticed the resource rename until now. I'll rework this PR soon.