Review `IsMostSenior` predicate

[yellowbean]

IsMostSenior bn bns ->
  let 
    bn1:bns1 =  (bndMap Map.!) <$> (bn:bns)
  in
    case (isPaidOff bn1,all isPaidOff bns1) of
      (False,True) -> True
      _ -> False

Currect logic should be

• if first bond is paid off, -> False
• if first bond is outstanding , ANY bond is paid off in rest bonds -> False
• otherwise -> True