Add tests for Compute cmdlets with -AsJob parameter

[maddieclayton]

Description

#5121

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[markcowl]

?? Seems like AcceptedValues should not be updated here

[markcowl]

(all the changes below to AcceptedValues seem incorrect)

[maddieclayton]

Updated - not sure why that happened.

[markcowl]

on demand run here: https://azuresdkci.westus2.cloudapp.azure.com/view/PowerShell/job/powershell-demand/317/