Ensure cleanup in e2e tests

[lentzi90]

/kind feature

Describe the solution you'd like

We do not currently check if the e2e tests clean up after themselves. I think we should do at least a naive comparison before and after the e2e test suite to see if some resources were forgotten. This will help us find cases where CAPO does not properly delete resources and also makes it safer to run the e2e tests on a "real" OpenStack cloud instead of devstack.

List the resource before and save the result.
List the resource after and compare. Report differences. Perhaps even fail the test if we can get this reliable enough.

Anything else you would like to add:

Listing everything in OpenStack is probably overkill. I imagine we would check something like:

• servers
• networks
• security groups
• load balancers
• volumes

Maybe also routers and ports if using pre-existing networks.
I think the check must be before and after the suite (not per test) since multiple tests can run simultaneously.

[lentzi90]

/help

[k8s-ci-robot]

@lentzi90:
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[mquhuy]

/assign