Add management command to clean up unreferenced bucket objects

[martinwe-adfinis]

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[martinwe-adfinis]

CI failing due to the tests running with ISOLATE_UNOCONV=true (which causes document-merge-service to invoke Unoconv with unshare, which is not supported for unprivileged processes anymore since Ubuntu 24.04).

Three ways out that I see:

• Don't run the tests with ISOLATE_UNOCONV=true. However, this means we won't get to test that case. --edit Just tried, that doesn't seem sufficient, for some reason it still invokes unshare, potentially there's another thing causing this.
• Check if it's possible to configure the runner to somehow allow unprivileged user namespaces.
• Revert to Ubuntu 22.04 as the runner image temporarily until we find a better solution (currently using ubuntu-latest, which happens to have changed to Ubuntu 24.04 recently).

[martinwe-adfinis]

• Don't run the tests with ISOLATE_UNOCONV=true. However, this means we won't get to test that case. --edit Just tried, that doesn't seem sufficient, for some reason it still invokes unshare, potentially there's another thing causing this

Turns out there's also a docker-compose.override.yml which set the same environment vars. When removing ISOLATE_UNOCONV=true there, it works.

However, we run into other issues, likely due to compatibility issues with Python (see this job), so that would need to be addressed as well.

• Check if it's possible to configure the runner to somehow allow unprivileged user namespaces.

I was unable to find any useful information on this until now. But given that this is about a kernel setting (whereas we are running our workloads in containers, where we have no way of touching kernel configs), I doubt this is possible.

To be fully thorough we could try to see how we can interact with the sysctl variables inside the runner, but I'd be highly surprised if we are able to somehow modify them.

• Revert to Ubuntu 22.04 as the runner image temporarily until we find a better solution (currently using ubuntu-latest, which happens to have changed to Ubuntu 24.04 recently).

I've done this for now and it seems to work (potentially we may want to split this to a separate PR, though). I'm now running into missing test coverage errors, but that is now truly related to my changes. 😄

[martinwe-adfinis]

Added the CI hack workaround via #933

This branch here is based on that other one, though, so this one is currently blocked.

[martinwe-adfinis]

#933 merged, this one here is ready for merge as well.