Log: libcrmservice: improve logs when cleaning up an operation

Previously, services_action_cleanup() got the sense of
dbus_pending_call_get_completed() wrong when logging a "did not complete"
message. It didn't really matter because the true case should never happen,
but this corrects it anyway.

This also slightly refactors to use services_set_op_pending() to clear the
pending call, to reduce code duplication, with the only real effect being to
log additional trace messages.