Create WebDeploy package which includes transform file (Web.Release.config) - don't apply transform. Also keeps the transform file as dependent so that the "preview-transform" functionality in Visual Studio works.

MSBuild arguments for VSTS

/p:DeployOnBuild=true /p:WebPublishMethod=Package /p:PackageAsSingleFile=true /p:SkipInvalidConfigurations=true /p:PackageLocation="$(build.artifactstagingdirectory)\\"

SomeWebProject.csproj

...
   <Import Project="$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props" Condition="Exists('$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props')" />
   <PropertyGroup>
     <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
+    <CopyAllFilesToSingleFolderForMsdeployDependsOn>
+      CustomCollectFiles;
+      $(CopyAllFilesToSingleFolderForMsdeployDependsOn);
+    </CopyAllFilesToSingleFolderForMsdeployDependsOn>
+    <TransformWebConfigEnabled>False</TransformWebConfigEnabled>
     <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
     <ProductVersion>
     </ProductVersion>

...
-    <None Include="Web.Release.config">
+    <Content Include="Web.Release.config">
       <IsTransformFile>True</IsTransformFile>
       <DependentUpon>Web.config</DependentUpon>
-    </None>
+    </Content>
   </ItemGroup>

...

+  <Target Name="CustomCollectFiles">
+    <ItemGroup>
+      <_CustomFiles Include="Web.Release.config" />
+      <FilesForPackagingFromProject  Include="%(_CustomFiles.Identity)">
+        <DestinationRelativePath>Web.Release.config</DestinationRelativePath>
+      </FilesForPackagingFromProject>
+    </ItemGroup>
+  </Target>  
 </Project>