Fix duplicate symbol file while packing

To fix the following build error:

```
/runtime/.dotnet/sdk/9.0.100-preview.7.24407.12/Sdks/NuGet.Build.Tasks.Pack/build/NuGet.Build.Tasks.Pack.targets(221,5): error NU5118: Warning As Error: File '/runtime/artifacts/bin/coreclr/linux.loongarch64.Release/IL/System.Private.CoreLib.pdb' is not added because the package already contains file 'runtimes/linux-loongarch64/lib/net9.0/System.Private.CoreLib.pdb' [/runtime/src/installer/pkg/sfx/Microsoft.NETCore.App/Microsoft.NETCore.App.Runtime.sfxproj]
```

Author: xen0n

src/coreclr/Directory.Build.targets

@@ -22,9 +22,8 @@
           Inputs="@(_DebugSymbolToMove)"
           Outputs="@(_DebugSymbolToMove->Metadata('Destination'))"
           Condition="'$(_DebugSymbolsProduced)' == 'true'">
-    <Copy SourceFiles="@(_DebugSymbolToMove)"
-          DestinationFiles="@(_DebugSymbolToMove->Metadata('Destination'))"
-          UseHardlinksIfPossible="false" />
+    <Move SourceFiles="@(_DebugSymbolToMove)"
+          DestinationFiles="@(_DebugSymbolToMove->Metadata('Destination'))" />
   </Target>
 
   <!-- Import targets here to have TargetPath and other macros defined. Limit to CoreLib. -->