Too many `VDisks` when no `Whiteboard` data

[artemmufazalov]

In storage/groups we use VDisk fields from Whiteboard for compatibility with viewer/storage. When Whiteboard is unavailable, we don't have VDiskId that is used as key in React. As a result, there is render issue when app renders more VDisks that are in the group.

How to reproduce - add such code to prepareGroupsResponse:

const VDiskId = Math.random() > 0.5 ? whiteboardVDisk?.VDiskId : undefined;

const whiteboardVDiskData = {
    ...whiteboardVDisk,
    VDiskId,