Remove the GeneratePackage property

That property was intended to enabled incremental servicing but with
now using the NuGet Pack task we can just make use of the publicl
available GeneratePackageOnBuild property.

Directory.Build.props

@@ -259,12 +259,6 @@
     <IsShippingAssembly Condition="$(IsExperimentalAssembly)">false</IsShippingAssembly>
     <!-- We don't want Private packages to be shipped to NuGet.org -->
     <IsShippingPackage Condition="$(MSBuildProjectName.Contains('Private')) or $(IsExperimentalAssembly)">false</IsShippingPackage>
-    <!-- A package isn't generated if in servicing or in runtimelab. Intended to be overridden at project level.
-         Excluding .sfxprojs as they have their own incremental servicing infra. -->
-    <GeneratePackage Condition="'$(GeneratePackage)' == ''">true</GeneratePackage>
-    <GeneratePackage Condition="(('$(PreReleaseVersionLabel)' == 'servicing' or
-                                  '$(GitHubRepositoryName)' == 'runtimelab') and
-                                 '$(MSBuildProjectExtension)' != '.sfxproj')">false</GeneratePackage>
     <PlaceholderFile>$(RepositoryEngineeringDir)_._</PlaceholderFile>
   </PropertyGroup>
 

Directory.Build.targets

@@ -1,4 +1,4 @@
-<Project InitialTargets="_OverridePackDependsOn">
+<Project>
   <PropertyGroup>
     <!--
     For non-SDK projects that import this file and then import Microsoft.Common.targets,
@@ -54,24 +54,8 @@
     <PackageDescription Condition="'$(PackageDescription)' == '' and '$(UseRuntimePackageDisclaimer)' == 'true'">$(RuntimePackageDisclaimer)</PackageDescription>
     <!-- Keep in sync as required by the Packaging SDK in Arcade. -->
     <Description>$(PackageDescription)</Description>
-    <GenerateNuspecDependsOn>ErrorForMissingPackageDescription;$(GenerateNuspecDependsOn)</GenerateNuspecDependsOn>
   </PropertyGroup>
 
-  <!-- Remove when https://github.com/NuGet/Home/issues/10405 is implemented and consumed. -->
-  <Target Name="ErrorForMissingPackageDescription"
-          Condition="'$(PackageDescription)' == ''">
-    <Error Text="Required property 'PackageDescription' is missing for $(MSBuildProjectName)." />
-  </Target>
-
-  <!-- <GeneratePackage /> controls if a package should be created by clearing out <PackDependsOn />. -->
-  <Target Name="_OverridePackDependsOn"
-          Condition="'$(IsPackable)' == 'true' and
-                     '$(GeneratePackage)' != 'true'">
-    <PropertyGroup>
-      <PackDependsOn />
-    </PropertyGroup>
-  </Target>
-
   <!--
     Arcade SDK versioning is defined by static properties in a targets file: work around this by
     moving properties based on versioning into a target.