Problem description: If a user imports an already existing template (to update it for example) with "Delete missing" set to true for "Template dashboards " and the import file doesn't have dashboards that exists in the current template version in frontend, then these dashboards will not be deleted after import.
Steps to reproduce:
- Export any existing template that has dashboards and graphs
- In the exported file delete all dashboards and all graphs
- Import this modified file with "Delete missing" flag set to true for Graphs and Templated dashboards
Result: Graphs are deleted after import, but dashboards are still there.
Expected: Dashboards that are missing in the import file should be deleted if the "Delete missing" flag is set