Fix for #247: Slyvote javascript error pMsgGrps[pGrpIdx] is undefined

Version 1.11: When configured to use all available sub-boards, still don't allow choosing a sub-board that has polls disabled. This fixes an issue where SlyVote was showing all available message groups but some could be empty due to having no sub-boards that allow polls.

enabled an automatic merge when the pipeline for 9817d68e succeeds

merged

mentioned in commit 55cc09eb

mentioned in commit f17258fe