As per title, all hosts running Icinga should be on Buster. Ideally by FQ2 FY20-21.
```
root@cumin1001:~# cumin 'P{O:alerting_host} and not P{F:lsbdistcodename = buster}'
2 hosts will be targeted:
icinga[1001,2001].wikimedia.org
DRY-RUN mode enabled, aborting
```
Action plan:
[x] Apply the role to alert2001 (new icinga host, T252032)
[] Verify all things are working as expected, i.e. state matches icinga1001, alert latency is acceptable, cpu load is lower (hw is more powerful) etc
[] Make sure metamonitoring is aware of alert2001 and checks are passing
[] Switchover icinga1001 -> alert2001 (enable notifications for alert2001, switch DNS)
[] Reimage alert1001 (see T255072) and repeat verification steps
[] Make sure metamonitoring is aware of alert1001 and checks are passing
[] Switch back alert2001 -> alert1001