VSD Usage overview - Display warning if background aggregations are not enabled

Background

The usage overview chart requires background aggregations to be enabled before the counts can be displayed in the chart.

Original discussion

Solution

• Check the status of background aggregations and supply that to the frontend app
• Display a warning message and link to enable background aggregations
• Replace 0 values with -

Designs

See #439699[VSD_Overview_panel_-_aggregation_not_enabled.png]