build: do not run GitHub actions for draft PRs

PR-URL: https://github.com/nodejs/node/pull/35910
Fixes: https://github.com/nodejs/node/issues/35899


Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Daijiro Wachi <daijiro.wachi@gmail.com>