test: switch to fixtures module

In test-file-read-noexist, switch from common.fixturesDir to the
fixtures module.

PR-URL: https://github.com/nodejs/node/pull/15880


Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>