ci: Test Kokoro's container as base for our container

.kokoro/gcp_windows_docker/Dockerfile

@@ -3,15 +3,16 @@
 # Chocolatey recommends starting with an image that already has .NET Framework 4.8 installed.
 # Kokoro supports up to Windows Server 2019 only.
 # We build in .NET 6 so we need to install .NET 6 after.
-FROM mcr.microsoft.com/dotnet/framework/runtime:4.8-windowsservercore-ltsc2019
+#FROM mcr.microsoft.com/dotnet/framework/runtime:4.8-windowsservercore-ltsc2019
+FROM us-central1-docker.pkg.dev/kokoro-container-bakery/kokoro/windows/windows2019/full:current
 
 # Setup Powershell
-RUN powershell -Command $ErrorActionPreference = 'Stop';
-RUN powershell -Command $ProgressPreference = 'SilentlyContinue';
+#RUN powershell -Command $ErrorActionPreference = 'Stop';
+#RUN powershell -Command $ProgressPreference = 'SilentlyContinue';
 
 # Install Chocolatey
-ENV ChocolateyUseWindowsCompression false
-RUN powershell -NoProfile -ExecutionPolicy Bypass -Command "iex ((New-Object System.Net.WebClient).DownloadString('https://chocolatey.org/install.ps1'))" && SET "PATH=%PATH%;%ALLUSERSPROFILE%\chocolatey\bin"
+#ENV ChocolateyUseWindowsCompression false
+#RUN powershell -NoProfile -ExecutionPolicy Bypass -Command "iex ((New-Object System.Net.WebClient).DownloadString('https://chocolatey.org/install.ps1'))" && SET "PATH=%PATH%;%ALLUSERSPROFILE%\chocolatey\bin"
 
 # Install .NET Core 3.0 which we need for Google.Apis.Auth.AspNetCore3
 RUN choco install -y --no-progress dotnetcore-3.0-sdk
@@ -24,4 +25,4 @@ RUN choco install -y --no-progress git
 
 # Default to PowerShell.
 # This is what Kokoro owned Docker images do. We'll do the same at least for now.
-CMD ["powershell.exe", "-NoLogo", "-ExecutionPolicy", "Bypass"]
+#CMD ["powershell.exe", "-NoLogo", "-ExecutionPolicy", "Bypass"]