Summary

Prevents a Kibana-crashing runtime error that can occur when deleting multiple controls.

From control_display_settings_popover.tsx:

 const isToRightOfGrowControl = useMemo(
    () => layoutEntry.order > 0 && Object.values(layoutState.controls)[layoutEntry.order - 1].grow,
    [layoutEntry.order, layoutState.controls]
  );

This can lead to a situation where layoutEntry.order - 1 might return undefined, and then throw a Kibana-crashing type error when undefined.grow didn't exist.

This is because when you delete controls, the remaining controls' order property doesn't get updated. So we could get into a situation where there are 3 controls, one of them has an order of 2, and if we delete controls 0 and 1, the sole existing control still has order: 2. It then tries to look up control at index 1, gets undefined, and errors out.

This PR recomputes control order when a control is deleted, preventing this error and any future situations that might arise from trying to look up controls based on their order