process: delay creation of process.env after bootstrap/node.js

Make sure that no code is allowed to access process.env during
the execution of bootstrap/node.js.

PR-URL: https://github.com/nodejs/node/pull/26515


Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: James M Snell <jasnell@gmail.com>