Fix a few codes associated to Errors

[Deleted user]

The unauthorized internal vault error is actually used for the SAML integration in vault. The code should be 401 instead of what's currently there:
https://github.com/scality/IronMan-Arsenal/blob/rel/1.0/errors/arsenalErrors.json#L608

[kf]

Yes you are right, I think it can be a good idea to have a talk with @jmunoznaranjo for that.