Fix user privileges (#1966)

* Revert "IndicesPrivileges can contain multiple queries (#1963)"

This reverts commit 3bc6627.

* Fix IndicesPrivileges and RoleTemplateScript

Author: swallez

output/schema/schema.json

@@ -21,5 +21,5 @@ import { Fields } from '@_types/common'
 
 export class FieldSecurity {
   except?: Fields
-  grant: Fields
+  grant?: Fields
 }