test: rename test-regress-nodejsGH-1726

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/sequential/test-regress-GH-1726.js → test/sequential/test-regress-child_process-exit.js

@@ -20,12 +20,13 @@
 // USE OR OTHER DEALINGS IN THE SOFTWARE.
 
 'use strict';
+require('../common');
+
 // Open a chain of five Node processes each a child of the next. The final
-// process exits immediately. Each process in the chain is instructed to
-// exit when its child exits.
+// process exits immediately. Each process in the chain is instructed to exit
+// when its child exits.
 // https://github.com/joyent/node/issues/1726
 
-require('../common');
 const assert = require('assert');
 const ch = require('child_process');