test: remove unnecessary skipIfWorker()

test-inspector-port-cluster passes in workers. Remove skipIfWorker()
from the test.

PR-URL: https://github.com/nodejs/node/pull/25427


Reviewed-By: Eugene Ostroukhov <eostroukhov@google.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>