Update the module names in AzureDiskEncryptionPreRequisiteSetup.ps1

[Jaykul]

Description

Change the #requires, since all the commands have already been changed to Az modules, and
Remove attempts at version sniffing, because there are no old versions of the Az.* modules

Checklist

• I have read the Submitting Changes section of CONTRIBUTING.md
• The title of the PR is clear and informative
• The appropriate change log has been updated
• The PR does not introduce breaking changes
• If applicable, the changes made in the PR have proper test coverage
• For public API changes to cmdlets:
  • the changes have gone through a cmdlet design review (Microsoft internal partners only)
  • the cmdlet markdown files were generated using the platyPS module

[adxsdkps]

Can one of the admins verify this patch?

[cormacpayne]

@azuresdkci add to whitelist

[cormacpayne]

@azuresdkci test this please