Slice-only TAS topology

[lchrzaszcz]

What type of PR is this?

/kind feature

What this PR does / why we need it:

This PR is a next step after #5353. This PR allows to define slice-level topology only without the main one. Effectively, that means the main topology is unconstrained.

Which issue(s) this PR fixes:

Relates to: #5439

Special notes for your reviewer:

Does this PR introduce a user-facing change?

NONE

[netlify]

✅ Deploy Preview for kubernetes-sigs-kueue ready!

Name	Link
🔨 Latest commit	ae7fa2e
🔍 Latest deploy log	https://app.netlify.com/projects/kubernetes-sigs-kueue/deploys/6852d7f1ca09f60008e9d159
😎 Deploy Preview	https://deploy-preview-5683--kubernetes-sigs-kueue.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify project configuration.

[k8s-ci-robot]

Hi @lchrzaszcz. Thanks for your PR.

I'm waiting for a kubernetes-sigs member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

I understand the commands that are listed here.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.

[gabesaba]

/ok-to-test

[mimowo]

Proposal to make it a bit more readable to users.

/release-note-edit

TAS: make specifying the PodSet topology level optional when 2-level scheduling is used, i.e.
when the PodSet slice topology level is specified with the `kueue.x-k8s.io/podset-slice-required-topology` annotation. 
In that case the scheduling mode for the PodSet level is assumed as "unconstrained".

[mimowo]

/lgtm
/approve
thanks 👍

[k8s-ci-robot]

LGTM label has been added.

Git tree hash: c112b5afccf7a9954df3fb7d4387b35123b031d0

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: lchrzaszcz, mimowo

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

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [mimowo]

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

[tenzen-y]

Proposal to make it a bit more readable to users.

/release-note-edit

TAS: make specifying the PodSet topology level optional when 2-level scheduling is used, i.e.
when the PodSet slice topology level is specified with the `kueue.x-k8s.io/podset-slice-required-topology` annotation. 
In that case the scheduling mode for the PodSet level is assumed as "unconstrained".

@mimowo TAS 2 level scheduling mechanisms have not been released yet. So I think we can remove release-note from this PR.

[mimowo]

Agree, we can drop it entirely

[tenzen-y]

/release-note-edit

NONE