CONTAP-425307: Detect invalid mailbox disks and prevent them from causing disabled takeover
Issue
After adding a shelf from another cluster, a foreign mailbox disk was imported with an incorrect sysid:
Mon Feb 24 11:32:09 +0100 [NetApp1-02: fmmbx_instanceWorker: fmmb_rcvryCredenceInfo_1:debug]: params: {'host': 'Partner', 'disk': '0a.03.10', 'mailboxId': '0365e4b0-387c-11ef-8104-d039eabe44fb', 'sysid': '5383xxxxx', 'sequenceNo': '272', 'credence': 'Sysid Foreign'}