[XamlC] Disable XamlC on non-Release builds

Author: StephaneDelcroix

.nuspec/Microsoft.Maui.Controls.targets

@@ -120,6 +120,7 @@
 		Condition=" '$(DesignTimeBuild)' != 'True' AND '@(MauiXaml)' != ''">
 	    <PropertyGroup>
 		<_MauiXamlCValidateOnly>$(MauiXamlCValidateOnly)</_MauiXamlCValidateOnly>
+		<_MauiXamlCValidateOnly Condition="'$(Configuration)' != 'Release' ">True</_MauiXamlCValidateOnly>
 		<_MauiXamlCValidateOnly Condition="'$(BuildingForLiveUnitTesting)' == 'True' ">True</_MauiXamlCValidateOnly>
 	    </PropertyGroup>
 		<XamlCTask