Grab sky map from superevent for RAVEN sky map comparison if from superevent IGWN alert

Currently there is a scenario where an IGWN alert trigger from adding a sky map to a superevent can still try to grab the sky map from the preferred event. A solution would be to pass an extra Boolean argument here that overwrites using the preferred event here.

changed milestone to %O4

added External Triggers RAVEN Priority labels

assigned to @naresh.adhikari

added to epic &5

changed the description

mentioned in merge request !1162 (merged)

closed with merge request !1162 (merged)

closed with commit b2154502