Revert "backport: chore: move cns from servercore to nanoserver (#2454)" (#3084)

Revert "backport: chore: move cns from servercore to nanoserver (#2454) (#2935)"

This reverts commit 73a0919.

Author: thatmattlong

cns/windows.Dockerfile

@@ -7,16 +7,13 @@ WORKDIR /usr/local/src
 COPY . .
 RUN GOOS=windows CGO_ENABLED=0 go build -a -o /usr/local/bin/azure-cns.exe -ldflags "-X main.version="$VERSION" -X "$CNS_AI_PATH"="$CNS_AI_ID"" -gcflags="-dwarflocationlists=true" cns/service/*.go
 
-# skopeo inspect --override-os windows docker://mcr.microsoft.com/windows/nanoserver:ltsc2019 --format "{{.Name}}@{{.Digest}}"
-FROM mcr.microsoft.com/windows/nanoserver@sha256:7f6649348a11655e3576463fd6d55c29248f97405f8e643cab2409009339f520 AS ltsc2019
+# intermediate for win-ltsc2019
+FROM mcr.microsoft.com/windows/servercore@sha256:6fdf140282a2f809dae9b13fe441635867f0a27c33a438771673b8da8f3348a4 as ltsc2019
 
-# skopeo inspect --override-os windows docker://mcr.microsoft.com/windows/nanoserver:ltsc2022 --format "{{.Name}}@{{.Digest}}"
-FROM mcr.microsoft.com/windows/nanoserver@sha256:244113e50a678a25a63930780f9ccafd22e1a37aa9e3d93295e4cebf0f170a11 AS ltsc2022
+# intermediate for win-ltsc2022
+FROM mcr.microsoft.com/windows/servercore@sha256:45952938708fbde6ec0b5b94de68bcdec3f8c838be018536b1e9e5bd95e6b943 as ltsc2022
 
-# skopeo inspect --override-os windows docker://mcr.microsoft.com/windows/nanoserver:ltsc2025 --format "{{.Name}}@{{.Digest}}" ## 2025 isn't tagged yet
-FROM mcr.microsoft.com/windows/nanoserver/insider@sha256:67e0ab7f3a79cd73be4a18bae24659c03b294aed0dbeaa624feb3810931f0bd2 AS ltsc2025
-
-FROM ${OS_VERSION} AS windows
+FROM ${OS_VERSION}
 COPY --from=builder /usr/local/src/cns/kubeconfigtemplate.yaml kubeconfigtemplate.yaml
 COPY --from=builder /usr/local/src/npm/examples/windows/setkubeconfigpath.ps1 setkubeconfigpath.ps1
 COPY --from=builder /usr/local/bin/azure-cns.exe azure-cns.exe