Disable mail to admins for problems with the database
With the incident of this evening, sysadmins got 12000 mails in their mailbox, they look like this:
```
Subject: [Django] ERROR (EXTERNAL IP): Internal Server Error: /
Internal Server Error: /
OperationalError at /
connection failed: connection to server on socket "/var/run/postgresql/.s.PGSQL.5432"
failed: FATAL: remaining connection slots are reserved for roles with the SUPERUSER
attribute
```
Given that database-level failures are likely to trigger wide-scale failures and trip the monitoring anyway, I suggest to find a way to exclude those exceptions from mails sent to admins.
/cc @helmutg
issue