Fixes for annuli with split sensors

Following discussions with @pagessin @hessey @ncalace this attempts to fix some issues with the annulus design definitions when splitting modules up into an element per row.

fyi @hhayward

NB !44381 (merged) touches some of the same files, and has been waiting to be included for some time, so it may be better to wait for this to go until after that is merged (although it may mean this MR needs some updates afterwards).