tools: do not run Corepack code before it's reviewed

Also enable running `make corepack-update` when `node`/`npm` is not
available globally.

PR-URL: #53405
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

Makefile

@@ -1151,13 +1151,14 @@ pkg: $(PKG)
 .PHONY: corepack-update
 corepack-update:
 	mkdir -p /tmp/node-corepack
-	curl -qLo /tmp/node-corepack/package.tgz "$$(npm view corepack dist.tarball)"
+	curl -qLo /tmp/node-corepack/package.tgz "$$($(call available-node,$(NPM) view corepack dist.tarball))"
 
 	rm -rf deps/corepack && mkdir deps/corepack
 	cd deps/corepack && tar xf /tmp/node-corepack/package.tgz --strip-components=1
 	chmod +x deps/corepack/shims/*
 
-	node deps/corepack/dist/corepack.js --version
+	$(call available-node,'-p' \
+			 'require(`./deps/corepack/package.json`).version')
 
 .PHONY: pkg-upload
 # Note: this is strictly for release builds on release machines only.