"Resume" action fails with Services not running that should be: ceilometer-agent-compute' when upgrading one-by-one from Ussuri to Victoria

[Aliaksandr Vasiuk]

Hi,

We noticed today, that when upgrading a cloud from Ussuri to Victoria in "one by one" manner, `resume` action fails with:
```
message: 'Action resume failed: Couldn''t resume: ceilometer-agent-compute didn''t
  resume cleanly.; Services not running that should be: ceilometer-agent-compute'
```

So, the cloud is:
* charmed openstack Focal Ussuri in a middle of upgrade to Focal Victoria.
* Control Plane is all Victoria.
* Juju 2.9.45
* nova-compute charm is: victoria/stable 727
* apt nova-compute packages are: 2:21.2.4-0ubuntu2.6
* all machines are Focal 20.04.6

Steps to reproduce:
* Pause nova unit
```
juju run-action --wait nova-compute/2 pause
```
* Resume nova-unit
```
juju run-action --wait nova-compute/2 resume
unit-nova-compute-2:
  UnitId: nova-compute/2
  id: "5963"
  message: 'Action resume failed: Couldn''t resume: ceilometer-agent-compute didn''t
    resume cleanly.; Services not running that should be: ceilometer-agent-compute'
  status: failed
  timing:
    completed: 2024-05-29 14:06:03 +0000 UTC
    enqueued: 2024-05-29 14:05:52 +0000 UTC
    started: 2024-05-29 14:05:52 +0000 UTC
```
* Nova unit is left in Blocked state.

I was able to reproduce it on:
* All nova units before "juju run <> openstack-upgrade"
* All nova units that was paused on Ussuri, then got upgraded with "juju run <> openstack-upgrade", then resume fails when unit is on Victoria
But when I pause and resume a unit that was already upgraded then everything is fine.

In case you need it: full output of failed resume action: https://pastebin.ubuntu.com/p/wKkXnDB3sN/

[Felipe Reyes (freyes)]

"""
    Failed to start ceilometer-agent-compute.service: Unit nova-compute.service is masked.
"""

I believe this is an ocurrence of this bug https://bugs.launchpad.net/charm-ceilometer-agent/+bug/1952882 , that's why newer releases of ceilometer-agent no longer have a pause/resume action - https://charmhub.io/ceilometer-agent/actions

[Aliaksandr Vasiuk (valexby)]

Ah, it is a duplicate of https://bugs.launchpad.net/charm-ceilometer-agent/+bug/1947585