[REF] 8.0 mgmtsystem_action

The current module inherit `crm.claim` while the `state` attribute doesn't exist anymore. I made some changes to use the `stage_id` instead but I'm not so sure it's a good idea. I'm open to suggestions.
Can't tell but the size limit here is strange. The reference is automatically created and it shouldn't be possible to change by hand. It will require to create a huge amount of document to run out of reference ids. Yet that's not impossible. I'll remove it.