Update package validation to 9.8.0 (#6716)

* Update package validation to 9.8.0

* Remove existing compatibility suppression files.

Author: joperezr

eng/MSBuild/Packaging.targets

@@ -37,7 +37,7 @@
     <!-- https://learn.microsoft.com/dotnet/fundamentals/package-validation/overview -->
     <EnablePackageValidation>true</EnablePackageValidation>
 
-    <PackageValidationBaselineVersion Condition=" '$(Stage)' == 'normal' ">9.7.0</PackageValidationBaselineVersion>
+    <PackageValidationBaselineVersion Condition=" '$(Stage)' == 'normal' ">9.8.0</PackageValidationBaselineVersion>
   </PropertyGroup>
 
   <!-- Verify that the minimum supported TFM is actually used. -->