src: change header file in node_stat_watcher.cc

change src/node_stat_watcher.cc to import `env-inl.h` instead of
`env.h`.

PR-URL: https://github.com/nodejs/node/pull/29976


Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>