After merging #240060, adding the sample data "[Logs] Visits" Discover session as a dashboard panel fails:

This is because the saved object no longer contains an ad hoc data view spec after converting it to be ES|QL based, but the Discover embeddable is expecting one. We don't require a data view spec in the SO schema, and there's really no reason it should be required for ES|QL tabs in Discover sessions. We likely never encountered this issue before since Discover sessions saved from Discover always embed an ad hoc data view spec for ES|QL tabs.