Comment 1 for bug 1898122

Adding IPADDRESS_TYPE.DISCOVERED to the condition at [0], causes the code to go to [1] when invoked by the release API, resulting in the delete of the IP similarly to how it is done in [2].

I also tested coding something similar to [3] which does ip=None and then ip.save, but in my testing the result was the same as ip.delete().

[0] https://github.com/maas/maas/blob/04a456af79ebdfd4858bd317f48e42959cc97670/src/maasserver/models/staticipaddress.py#L876

[1] https://github.com/maas/maas/blob/04a456af79ebdfd4858bd317f48e42959cc97670/src/maasserver/models/interface.py#L1189

[2] https://github.com/maas/maas/blob/04a456af79ebdfd4858bd317f48e42959cc97670/src/maasserver/rpc/leases.py#L149

[3] https://github.com/maas/maas/blob/04a456af79ebdfd4858bd317f48e42959cc97670/src/maasserver/rpc/leases.py#L212