Update Deviceupdate project file (Azure#26585)

* use Azure.Core and Azure.Core.Experimental package

Author: chunyu3

sdk/deviceupdate/Azure.IoT.DeviceUpdate/Azure.IoT.DeviceUpdate.sln

@@ -15,10 +15,6 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Azure.Test.Perf", "..\..\..
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "DeviceUpdateClientSample", "samples\DeviceUpdateClientSample\DeviceUpdateClientSample.csproj", "{4719AE90-2B90-4DBC-92DA-8CCE29D5B7F3}"
 EndProject
-Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Azure.Core", "..\..\core\Azure.Core\src\Azure.Core.csproj", "{85677AD3-C214-42FA-AE6E-49B956CAC8DC}"
-EndProject
-Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Azure.Core.Experimental", "..\..\core\Azure.Core.Experimental\src\Azure.Core.Experimental.csproj", "{8B372926-5A38-4219-879F-67D95F292CDA}"
-EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU

sdk/deviceupdate/Azure.IoT.DeviceUpdate/src/Azure.IoT.DeviceUpdate.csproj

@@ -34,9 +34,9 @@
     <Compile Include="$(AzureCoreSharedSources)OperationInternalOfT.cs" LinkBase="Shared" />
     <Compile Include="$(AzureCoreSharedSources)AzureResourceProviderNamespaceAttribute.cs" LinkBase="Shared" />
   </ItemGroup>
-  <ItemGroup>
-    <ProjectReference Include="..\..\..\core\Azure.Core.Experimental\src\Azure.Core.Experimental.csproj" />
-    <ProjectReference Include="..\..\..\core\Azure.Core\src\Azure.Core.csproj" />
+<ItemGroup>
+    <PackageReference Include="Azure.Core" />
+    <PackageReference Include="Azure.Core.Experimental" />
   </ItemGroup>
 
 </Project>