test: covering destroying when worker already disconnected

This test covers 374 line in lib/internal/cluster/master
that was uncovered by previous tests

test/parallel/test-cluster-call-and-destroy.js

@@ -0,0 +1,15 @@
+'use strict';
+const common = require('../common');
+const cluster = require('cluster');
+const assert = require('assert');
+
+if (cluster.isMaster) {
+  const worker = cluster.fork();
+  worker.on('disconnect', common.mustCall(() => {
+    assert.strictEqual(worker.isConnected(), false);
+    worker.destroy();
+  }));
+} else {
+  assert.strictEqual(cluster.worker.isConnected(), true);
+  cluster.worker.disconnect();
+}