Deprovisioning a user fails when already deprovisioned

[phavekes]

This issue is imported from pivotal - Originaly created at Sep 19, 2022 by Bart Geesink

When I try to deprovision a user from Middleware which has been deprovisioned before, it will fail with the following message:

{"name":"OpenConext Stepup","status":"FAILED","data":[],"message":"Operation on this Identity is not allowed: it has been forgotten"}

That should not be an error, the deprovision command should be idempotent. Other apps will answer an OK, with empty data:
[{"name":"EngineBlock","status":"OK","data":[]}

I suggest we do the same for middleware