MultiKueue: performance testing

**What would you like to be added**:

Performance test for MultiKueue .

We would like to observe the rate of processing workloads assuming there are 3 (or so) worker clusters.

I imagine this is a dedicated CI job. It will be hard in OSS on kind to get beyond 3 clusters probably, or otherwise we will anyway saturate the resources of the host node running the CI job.

**Why is this needed**:

To allow detecting performance regressions in MultiKueue.

**Completion requirements**:

This enhancement requires the following artifacts:

- [ ] Design doc
- [ ] Docs update

The artifacts should be linked in subsequent comments.