L3 - Default Description
On Upgrading of a templated index, we don't currently handle the deletion of the old template. We should either delete the old template or instead rather than create a new template for the target index, update the old template.
ATs:
- No unused templates remain after upgrade of a templated index
- The template assertion in UpgradeEsSchemaIT is reenabled
- (Optional) We delete all existing old templates in case there are any from before