Add timeout to integration tests LXD container removal

[bschimke95]

Sometimes the removing an LXD container is stuck forever. Adding a timeout prevents the CI from hanging indefinitely in this case.
It is very likely that this happens because of how we configure the LXD profile. Since this will undergo significant changes in the future, I did not dig too deeply into this issue.
https://discourse.ubuntu.com/t/lxd-containers-not-removed-in-ci-even-with-force-flag/49039

[louiseschmidtgen]

Can we please add a TODO here with a note to make a proper fix.
IMHO, we should rather work on a fix before we keep this timeout in forever.
If we add a timeout I would much rather put a timeout on the entire test to avoid it getting stuck for 6 hours.

[bschimke95]

Several reasons why I put the timeout here instead of on the test level:

1. This is a infra-specific bug. It would be unnecessary to limit this for non-LXD runs.
2. We don't want the CI to fail because of this issue. AFAIK setting a timeout on the test level would fail the suite.

"IMHO, we should rather work on a fix before we keep this timeout in forever."
That's not so straight forward. As discussed, a proper fix requires some investigation which takes time (we have a card for that). This workaround unblocks us and TBH I don't see any issue that we could realistically face with that.

That being said, I added a comment/TODO.

[HomayoonAlimohammadi]

Thanks a lot @bschimke95! LGTM.