feat: bump windows image version for 2026-03B (#8074)

Co-authored-by: Jane Jung <janejung@microsoft.com>
Co-authored-by: janenotjung-hue <107402425+janenotjung-hue@users.noreply.github.com>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
Co-authored-by: aks-node-assistant[bot] <190555641+aks-node-assistant[bot]@users.noreply.github.com>

Author: 3 people