test: remove message from asserts

PR-URL: https://github.com/nodejs/node/pull/15920
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>

test/parallel/test-cluster-worker-init.js

@@ -33,9 +33,9 @@ if (cluster.isMaster) {
   const worker = cluster.fork();
 
   worker.on('message', common.mustCall((message) => {
-    assert.strictEqual(message, true, 'did not receive expected message');
+    assert.strictEqual(message, true);
     const w = worker.disconnect();
-    assert.strictEqual(worker, w, 'did not return a reference');
+    assert.strictEqual(worker, w);
   }));
 
   worker.on('online', () => {