Why

The recent spice-vdagent update causes all virtual machines to take 90 seconds longer on every shutdown/reboot:
https://bugzilla.redhat.com/show_bug.cgi?id=1813667
The service hangs when systemd tries to stop it, and systemd then kills it after a 90 second timeout expires.

This is a recurring pattern, I saw services blocking shutdown/reboot in the past, and so far we haven't been able to do anything about it from a blocker perspective. I think that for cases where the problem occurs very frequently or every time, we should have a way to block the release until it's fixed. I find it a very poor experience to wait 90+ seconds for machine reboot/shutdown. Much poorer than, say, a crashing desktop application (which we block on), because that application can be replaced with a different one. System services mostly can't be replaced, and certainly not by a general user.

Proposal

So I propose to amend the "System services" criterion [1]:

```
All system services present after installation with one of the release-blocking package sets must start properly, unless they require hardware which is not present.
```

with something like this:

```
All system services present after installation with one of the release-blocking package sets must start properly, unless they require hardware which is not present.

All system services present after installation with one of the release-blocking package sets must not time out frequently or regularly when they are being stopped during system reboot/shutdown.
```

The way it is written, the mentioned bug would be a conditional violation of that criterion (applies only to VMs) and we'd need to use our judgement to determine whether it's a blocker.

Thoughts?

[1] https://fedoraproject.org/wiki/Fedora_32_Final_Release_Criteria#System_services