Avoid unnecessary deps in M.E.Logging.Abstractions (#59162)

Fixes #59161

The System.Buffers and System.Memory packages are
dependencies of the net6.0 M.E.Logging.Abstractions
library even though these libraries are part of the
.NETCoreApp shared framework.

It's undesirable to have the dependencies in the graph
as these aren't built live anymore and are only serviced
on demand.

Author: ViktorHofer

src/libraries/Microsoft.Extensions.Logging.Abstractions/src/Microsoft.Extensions.Logging.Abstractions.csproj

@@ -30,7 +30,7 @@ Microsoft.Extensions.Logging.Abstractions.NullLogger</PackageDescription>
              Link="Common\System\Text\ValueStringBuilder.cs" />
   </ItemGroup>
 
-  <ItemGroup>
+  <ItemGroup Condition="'$(TargetFrameworkIdentifier)' != '.NETCoreApp'">
     <PackageReference Include="System.Buffers" Version="$(SystemBuffersVersion)" />
     <PackageReference Include="System.Memory" Version="$(SystemMemoryVersion)" />
   </ItemGroup>