ci: mount the NuGet cache in Agent restore stages [CI]

ci/restore-linux-dependencies.sh

@@ -140,6 +140,7 @@ PY
     python3 "$root/ci/stage-node-image.py" agent "$rid" "$context"
     echo "restoring Agent dependencies for $rid"
     python3 "$root/ci/run-with-timeout.py" 1800 buildah bud --layers --force-rm --network host --tls-verify=true --arch amd64 \
+      --volume "$NUGET_PACKAGES:/root/.nuget/packages:z" \
       --build-arg "NATIVEAOT_BUILDER_IMAGE=$builder_image" \
       --build-arg "NODE_RID=$rid" --build-arg "STATIC_MSQUIC=$static_msquic" \
       -f "$root/packaging/container/Agent.Restore.Containerfile" \