Refactor: libpacemaker: Unpack status in pcmk__schedule_actions()

pcmk__schedule_actions() expects that cluster_status() has already been
called, so just do it at the beginning. cluster_status() now checks
whether it's already been called and returns early if so, so this is
safe.

We actually did something similar in pcmkschedule_actions() until a
few commits ago, but the intermediate commits were clearer without
pcmkschedule_actions() calling cluster_status().

Signed-off-by: Reid Wahl <nrwahl@protonmail.com>