How can I identify which Dashboards contain a specific saved search?
You can use rest command to find specific savedsearch used in any dashboard. Try this one,
|rest /servicesNS/admin/search/data/ui/views
| fields "eai:data" "eai:acl.app" label id
| where like('eai:data',"%<<YOUR_SS_NAME>>%")
| table "eai:acl.app" label id
Replace <<YOUR_SS_NAME>> with your savedsearch name.