test: rename test-regress-nodejsGH-4256

Rename the test appropriately alongside mentioning the subsystem
Also, make a few basic changes to make sure the test conforms
to the standard test structure

Refs: nodejs#19105
Refs: https://github.com/nodejs/node/blob/master/doc/guides/writing-tests.md#test-structure

test/parallel/test-regress-GH-4256.js → test/parallel/test-process-domain-segfault.js

@@ -21,6 +21,11 @@
 
 'use strict';
 require('../common');
+
+// This test ensures that setting `process.domain` to `null` does not result in
+// node crashing with a segfault
+// https://github.com/nodejs/node-v0.x-archive/issues/4256
+
 process.domain = null;
 setTimeout(function() {
   console.log('this console.log statement should not make node crash');