Frontend: Update election status page for CSB

[lama-d3v]

See Figma: https://www.figma.com/design/zZlFr8tYiRyp4I26sh6eqp/Kiesraad---Abacus-optelsoftware?node-id=17352-277132&m=dev

• For a CSB no alert should be shown that there are no polling stations.
• Should not be possible to maintain polling stations
• Also update status in overview page (check in tests)