[_ValidateAndroidPackageProperties] can we skip this MSBuild target during Design-Time builds?

[jonathanpeppers]

Steps to Reproduce

1. The _ValidateAndroidPackageProperties target is running during Design-Time Builds, and doesn't look like it is needed?

15.8:

18 ms  _ValidateAndroidPackageProperties          1 calls

Current master:

29 ms  _ValidateAndroidPackageProperties          1 calls

Might just be slower in master, because I had a Debug build of XA.

https://github.com/xamarin/xamarin-android/blob/e4c15751253ed56cfedfd9d428d6129a5727462a/src/Xamarin.Android.Build.Tasks/Xamarin.Android.Common.targets#L638-L665

What should we do?

See if we can skip this target if $(DesignTimeBuild) is true.