Metaqueries doesn't work on Grafana 8.0.3

[adsail]

MetaQueries does not plot on Grafana 8.0.3 panels (both of type Graph (old) and Time series).

Expected in the screenshots below are series values at 20GB.

[sjoeboo]

Found that panels migrated from a grafana 6.x install keep working, but the identical panel, hand created in Grafana 8.x does not.

Diffing the panel jsons, i found the panel created in the 8.x release does not contain "datasource": "MetaQueries", in the metaquery query, where as the working one does.

[asaf400]

#155