test: fix lint error

Fix lint error introduced 03550a5c1e. Unused module `fs` is removed.

PR-URL: https://github.com/nodejs/node/pull/16145
Ref: https://github.com/nodejs/node/pull/15832#issuecomment-335808467
Reviewed-By: Bradley Farias <bradley.meck@gmail.com>
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

test/parallel/test-tls-net-connect-prefer-path.js

@@ -12,7 +12,6 @@ common.refreshTmpDir();
 
 const tls = require('tls');
 const net = require('net');
-const fs = require('fs');
 const assert = require('assert');
 
 function libName(lib) {