test: fix typo in inspector-helper.js

PR-URL: https://github.com/nodejs/node/pull/36127


Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Daijiro Wachi <daijiro.wachi@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>