Upgrade FSLogix just in case

[eponerine]

While you would assume the images from MSFT will have the latest FSLogix agent in them, this should probably be commented out to ensure the latest and greatest is in fact installed (FSLogix doesn't follow a release cadence like Windows Updates).

And even if the downloaded version matches what is already installed, it will gracefully exit during upgrade.

https://github.com/microsoft/MSLab/blob/60293c874319370e0a16e45a4f7ae08480218e6f/Scenarios/AzSHCI%20and%20AVD/Scenario.ps1#L1447-L1459