Use static version of node for all builds, not just darwin

This way, building a standalone release locally and putting it in the
release contianer for testing is less likely to break.

ci/build/clean.sh

@@ -13,7 +13,8 @@ main() {
     release-gcp \
     release-images \
     dist \
-    .cache
+    .cache \
+    node-*
 
   pushd lib/vscode
   git clean -xffd

ci/steps/release-packages.sh

@@ -4,11 +4,11 @@ set -euo pipefail
 main() {
   cd "$(dirname "$0")/../.."
 
-  if [[ $OSTYPE == darwin* ]]; then
-    NODE_VERSION=v12.18.3
-    curl -L "https://nodejs.org/dist/$NODE_VERSION/node-$NODE_VERSION-darwin-x64.tar.gz" | tar -xz
-    PATH="$PWD/node-$NODE_VERSION-darwin-x64/bin:$PATH"
-  fi
+  NODE_VERSION=v12.18.3
+  NODE_OS="$(uname | tr '[:upper:]' '[:lower:]')"
+  NODE_ARCH="$(uname -m | sed 's/86_64/64/; s/aarch64/arm64/')"
+  curl -L "https://nodejs.org/dist/$NODE_VERSION/node-$NODE_VERSION-$NODE_OS-$NODE_ARCH.tar.gz" | tar -xz
+  PATH="$PWD/node-$NODE_VERSION-$NODE_OS-$NODE_ARCH/bin:$PATH"
 
   # https://github.com/actions/upload-artifact/issues/38
   tar -xzf release-npm-package/package.tar.gz