wocky-pubsub-service-test: factor out create_node_test
wocky-pubsub-service-test: factor out create_node_test

noonien-d/wocky,freedesktop-unofficial-mirror/wocky,freedesktop-unofficial-mirror/wocky,freedesktop-unofficial-mirror/wocky,noonien-d/wocky,noonien-d/wocky