A follow up to https://github.com/RedHatInsights/chrome-service-backend/pull/506

The backend now supports default definitions for each of the layout sizes (sm, md, lg, xl)
Let's update the defaults for non-xl sizes to look good in the UI.

Link to docs:
https://github.com/RedHatInsights/chrome-service-backend/blob/main/docs/dashboard-layouts.md#base-layout-updates

JSONSchema attributes information and validation:
https://github.com/RedHatInsights/chrome-service-backend/blob/main/widget-dashboard-defaults/widget-schema.json