Jungfrau: Investigate why why didn't get an error when the `trigger_mode` signal failed to set

During Jungfrau testing, there was an instance where the `trigger_mode` completed a set in ophyd-async, even though the RBV value was never actually matching. We should investigate why ophyd-async didn't check the signal against its RBV value when determining when the set was complete. It could be due to there being different PVs for the setting and reading, and could also be related to connecting signals with the `fastcs_connector`