msi: Make MsiInstallProduct conformance test depend on proper UI level processing.

[Misha Koshelev]

> Well, by definition, that's not really a conformance test because it
> doesn't conform to windows.  Did you make the property public and add
> the property to the Property table?
> 
> http://msdn2.microsoft.com/en-us/library/aa370912.aspx
> 

Aha, google search figured it out:

* Property name ALL CAPS - passed from UI to execute.
* otherwise not.

Too bad it's not documented on msdn (you think they would...)

Misha