Flight Plan: changing Map source causes map to re-center

Changing the map source drop-down on the Flight Plan screen causes the map to re-center on the vehicle. Really it should leave the map's centering and zoom untouched.

Reproduce the behavior on the Flight Plan screen by changing the map source from its drop-down, then trace the map update path from that control. Done means changing the source leaves the map's current center and zoom untouched while the new source is displayed.

Written by the indexing model from the issue text.