test: remove NODE_DEBUG in global module loading test

Otherwise the debug log output might be mixed up with
the expected errors and the assertion matching the error
message would fail.

PR-URL: nodejs#19177
Refs: nodejs#19112
Reviewed-By: Gus Caplan <me@gus.host>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>

test/parallel/test-module-loading-globalpaths.js

@@ -41,8 +41,6 @@ if (process.argv[2] === 'child') {
   const testFixturesDir = fixtures.path(path.basename(__filename, '.js'));
 
   const env = Object.assign({}, process.env);
-  // Turn on module debug to aid diagnosing failures.
-  env.NODE_DEBUG = 'module';
   // Unset NODE_PATH.
   delete env.NODE_PATH;