Finalize KubeVirt integrations

[NouemanKHAL]

What does this PR do?

Handles some comments from the KubeVirt PRs:

• Add kubevirt_api integration #18179
• Add kubevirt_controller integration #18186
• Add kubevirt_handler integration #18283

Motivation

Synchronize all the 3 integrations to follow the same behavior:

• Add missing metric units.
• Handle namespace label collision with the kubename space (rename namespace -> vm_namespace).
• Use the same metric description for the can_connect metric.

Additional Notes

For the kubevirt_handler, and kubevirt_controller metrics, the only metric that contains the namespace label are kubevirt_vmi and kubevirt_vm metrics, I confirmed that using:

➜ $ cat kubevirt_controller/tests/fixtures/metrics.txt | grep "namespace=" | cut -c1-12 | sort | uniq
kubevirt_vm_
kubevirt_vmi
➜  $ cat kubevirt_handler/tests/fixtures/metrics.txt | grep "namespace=" | cut -c1-12 | sort | uniq
kubevirt_vmi
➜  $ cat kubevirt_api/tests/fixtures/metrics.txt | grep "namespace=" | cut -c1-12 | sort | uniq
➜  

Both metrics share the same label values name="aws-kubevirt-vm-6",namespace="default" referring to the VM resource, example:

kubevirt_vm_starting_status_last_transition_timestamp_seconds{name="aws-kubevirt-vm-6",namespace="default"} 0
kubevirt_vmi_non_evictable{name="aws-kubevirt-vm-6",namespace="default",node="ip-192-168-58-28.eu-west-3.compute.internal"} 0

So we can safely rename the namespace label to vm_namespace to avoid collision with the namespace tag attached by the agent on Kubernetes which is different than the namespace where the VM is running.

Review checklist (to be filled by reviewers)

• Feature or bugfix MUST have appropriate tests (unit, integration, e2e)
• Changelog entries must be created for modifications to shipped code
• Add the qa/skip-qa label if the PR doesn't need to be tested during QA.
• If you need to backport this PR to another branch, you can add the backport/<branch-name> label to the PR and it will automatically open a backport PR once this one is merged

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 86.77%. Comparing base (fcbaaa1) to head (e073b32).
Report is 27 commits behind head on master.

Additional details and impacted files

Flag	Coverage Δ
activemq	?
cassandra	?
hive	?
hivemq	?
hudi	?
ignite	?
jboss_wildfly	?
kafka	?
kubevirt_api	82.44% <ø> (ø)
kubevirt_controller	85.36% <ø> (ø)
kubevirt_handler	91.32% <ø> (ø)
presto	?
solr	?

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