wocky-xmpp-scheduler-test: use test_{open,from}_connection from test helper
wocky-xmpp-scheduler-test: use test_{open,from}_connection from test helper

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