test: remove message argument in cluster setup test

In test/parallel/test-cluster-setup-master-cumulative.js:

Remove the message parameter to ensure that the compared
objects are printed out. Add the original message as a
comment above.

PR-URL: https://github.com/nodejs/node/pull/16838


Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>