Update SIG Node CI test coverage guide

[natasha41575]

Here is a proposal for how we can reorganize the SIG Node CI testgrid to make tests easier to find. I generally find it hard to navigate the current testgrid; it is not obvious (at least to me) where or if a particular test is running in the testgrid today.

This came out of me picking up kubernetes/kubernetes#134862; while starting to look at what we had previously defined as our test coverage guidance (which is still not implemented), I thought the current proposal can be improved. This is intended to be an incremental improvement, and can be iterated upon in the future. I also want to be careful not to remove any existing test coverage.

Also another, note, there are some highly specialized test tabs like sig-node-problem-detector, sig-node-security-profiles-operator, sig-node-ec2, sig-node-gpu etc, I don't intend to touch those.

All feedback and suggestions are welcome. I am not an expert on test-infra or all node features so please feel free to bring up issues or mistakes :)

/sig node

/assign @SergeyKanzhelev
/cc @mariafromano-25 @haircommander @kannon92

/hold
just to gate merging until we are ready

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: natasha41575
Once this PR has been reviewed and has the lgtm label, please assign haircommander for approval. For more information see the Code Review Process.

The full list of commands accepted by this bot can be found here.

Details

Needs approval from an approver in each of these files:

• config/jobs/kubernetes/sig-node/OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[haircommander]

curious why fedora was dropped? they're the only cri-o tests AFAIU

[natasha41575]

ah I can put them back for cri-o, thanks for the callout!

[haircommander]

I know we sometimes struggle to keep them green but I'd love cri-o tests to be kept here if possible

[haircommander]

/triage accepted
/priority important-longterm