bind restarts many times during the day

MAAS 3.3.5
We noticed in test runs that our staticaly defined VIP addresses for openstack services sometimes don't resolve and a minute later they are fine.
Turns out bind server restarts often, tens of times a day.

```
$ grep "starting BIND" named.log*|awk '{print $1}'|sed "s/.*://"|sort|uniq -c
     15 12-Oct-2023
     67 13-Oct-2023
    175 14-Oct-2023
    170 15-Oct-2023
     34 16-Oct-2023
     41 17-Oct-2023
     36 18-Oct-2023
     73 19-Oct-2023
     15 20-Oct-2023

```

Christian had a look and he found that BIND is getting restarted frequently because MAAS checks the serial for each zone it updates, if it fails the check on 2 additional retries, BIND is restarted. But reason is unknown.

To show how it is hitting us I ran a script which digs six statically defined records once a minute, it failed 56 times during 12 hours, there were several cases when they were not resolving for two minutes.