Use shared Arcade scripts in Azure Linux 4.0

Author: Copilot

src/azurelinux/4.0/net11.0/crossdeps-builder/amd64/Dockerfile

@@ -1,3 +1,7 @@
+# Arcade rootfs cross-build scripts, provided as a separate image so they can be copied
+# in without requiring the repo root as the Docker build context. See eng/cross-scripts.Dockerfile.
+FROM mcr.microsoft.com/dotnet-buildtools/prereqs:cross-scripts-amd64 AS cross-scripts
+
 FROM mcr.microsoft.com/azurelinux-beta/base/core:4.0
 
 ARG PIP_INDEX_URL
@@ -131,12 +135,8 @@ RUN \
 
 ENV PATH="/opt/llvm/bin:$PATH"
 
-# Obtain arcade scripts used to build rootfs
-ARG ARCADE_COMMIT=e5f974ba880c3da69932191c665e90ee64e8da26
-RUN git config --global user.email builder@dotnet-buildtools-prereqs-docker && \
-    git init /scripts && \
-    git -C /scripts fetch --depth 1 https://github.com/dotnet/arcade ${ARCADE_COMMIT} && \
-    git -C /scripts checkout --detach FETCH_HEAD
+# Copy arcade scripts used to build rootfs
+COPY --from=cross-scripts /eng/common/cross/ /scripts/eng/common/cross/
 
 # Clear PIP_INDEX_URL since it contains a short-lived token that should not persist in the final image
 ENV PIP_INDEX_URL=