test: remove unneeded test statement

The statement removed was added in 6657b15 but it was not added
as an assertion. It currently returns false but t0he test does not fail
because of the missing assertion. Since the property is no longer one
that exists, there is no need to test its existence. Remove the line.

PR-URL: #41663
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Mestery <mestery@protonmail.com>
Reviewed-By: Darshan Sen <raisinten@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Tierney Cyren <hello@bnb.im>

Author: Trott

test/parallel/test-event-emitter-subclass.js

@@ -36,8 +36,6 @@ function MyEE(cb) {
 
 const myee = new MyEE(common.mustCall());
 
-myee.hasOwnProperty('usingDomains');
-
 Object.setPrototypeOf(ErrorEE.prototype, EventEmitter.prototype);
 Object.setPrototypeOf(ErrorEE, EventEmitter);
 function ErrorEE() {