test: fix too optimistic guess in setproctitle

PR-URL: nodejs#12792
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

test/parallel/test-setproctitle.js

@@ -14,7 +14,7 @@ const path = require('path');
 // The title shouldn't be too long; libuv's uv_set_process_title() out of
 // security considerations no longer overwrites envp, only argv, so the
 // maximum title length is possibly quite short.
-let title = 'test';
+let title = String(process.pid);
 
 assert.notStrictEqual(process.title, title);
 process.title = title;