Set PackageValidationBaselineName to assemblyName when packageID is not set (#18658)

* set PackageValidationBaselineName to assembly name when packageID is not set.

* use value or default

Co-authored-by: Viktor Hofer <viktor.hofer@microsoft.com>

* Apply suggestions from code review

Co-authored-by: Viktor Hofer <viktor.hofer@microsoft.com>

* inlining the PackageValidationBaselineName

* Apply suggestions from code review

Co-authored-by: Viktor Hofer <viktor.hofer@microsoft.com>

Co-authored-by: Viktor Hofer <viktor.hofer@microsoft.com>

Author: Anipik

src/Compatibility/Microsoft.DotNet.PackageValidation/build/Microsoft.DotNet.PackageValidation.targets

@@ -2,19 +2,16 @@
 <Project>
   <UsingTask TaskName="Microsoft.DotNet.PackageValidation.ValidatePackage" AssemblyFile="$(DotNetPackageValidationAssembly)" />
 
-  <PropertyGroup>
-    <PackageValidationBaselineName>$([MSBuild]::ValueOrDefault('$(PackageValidationBaselineName)', '$(PackageId)'))</PackageValidationBaselineName>
-  </PropertyGroup>
-
   <ItemGroup Condition="'$(PackageValidationBaselinePath)' == '' and '$(PackageValidationBaselineVersion)' != ''">
-    <PackageDownload Include="$(PackageValidationBaselineName)" Version="[$(PackageValidationBaselineVersion)]" />
+    <PackageDownload Include="$([MSBuild]::ValueOrDefault('$(PackageValidationBaselineName)', '$(PackageId)'))" Version="[$(PackageValidationBaselineVersion)]" />
   </ItemGroup>
 
   <Target Name="RunPackageValidation"
           AfterTargets="Pack"
           Condition="'$(IsPackable)' == 'true'">
 
     <PropertyGroup>
+      <PackageValidationBaselineName Condition="'$(PackageValidationBaselineName)' == ''">$(PackageId)</PackageValidationBaselineName>
       <PackageValidationBaselinePath Condition="'$(PackageValidationBaselinePath)' == '' and '$(PackageValidationBaselineVersion)' != ''">$([MSBuild]::NormalizePath('$(NuGetPackageRoot)', '$(PackageValidationBaselineName.ToLower())', '$(PackageValidationBaselineVersion)', '$(PackageValidationBaselineName.ToLower()).$(PackageValidationBaselineVersion).nupkg'))</PackageValidationBaselinePath>
       <GenerateCompatibilitySuppressionFile Condition="'$(GenerateCompatibilitySuppressionFile)' == ''">false</GenerateCompatibilitySuppressionFile>
       <_compatibilitySuppressionFilePath>$([MSBuild]::NormalizePath('$(MSBuildProjectDirectory)', 'CompatibilitySuppressions.xml'))</_compatibilitySuppressionFilePath>