[10.0][mis_builder] Cannot delete mis report template if it contains sub kpi's

[JordiBForgeFlow]

Testing #275
If I define a mis report template with sub-kpi's, when I try to delete the whole report template I get the error:

`The operation cannot be completed, probably due to the following:

• deletion: you may be trying to delete a record while other records still reference it
• creation/update: a mandatory field is not correctly set

[object with reference: mis.report.subkpi - mis.report.subkpi]
`

Perhaps a delete=on_cascade should be added

cc @sbidoul

[sbidoul]

Should be fixed in 1d480d2. Thanks for reporting!

[JordiBForgeFlow]

Works correctly now. Thanks!