Allow update of a mailbox waiting for a password

[mjeammet]

Bug Report

Problematic behavior
When I try to deactivate a mailbox, if the mailbox is waiting for a password but doesn't have any, it currently triggers

• a very ugly error 500 in the admin
• "Impossible de mettre à jour le statut de la boîte mail." in front

Expected behavior/code
I expect an admin to be able to disable a mailbox, even though it's used by the Identity Provider.

Or at least, a clearer message for people for debug/admin intervention.

Steps to Reproduce

1. Created a mailbox with (must have been the default at some point)
2. Try to disable or update the mailbox in anyway
3. Bam, error

Environment

• People version: 1.15.0