Enable periodic integration tests in prow

[ivanvc]

What would you like to be added?

We recently enabled periodic integration tests for 1 CPU in prow (kubernetes/test-infra#33894 / #18976 (comment)). After seeing them running for the last week (https://testgrid.k8s.io/sig-etcd-periodics), we should also enable 2 CPU and 4 CPU jobs.

As a reference, take a look at the pull request: https://github.com/kubernetes/test-infra/pull/33894/files

The current definitions for the presubmit jobs for 2 and 4 CPUs are here:

• 2 CPUs AMD64
• 2 CPUs ARM64
• 4 CPUs AMD64
• 4 CPUs ARM64

The periodic job definition is very similar. However, we need the following changes:

1. Replace the "pull" prefix from the job name with "ci"
2. Drop always_run and branches, i.e.,

   always_run: true
   branches:
     - main
     - release-3.5

3. Add interval set to 24h and extra_refs, i.e.

     interval: 24h
     extra_refs:
       - org: etcd-io
         repo: etcd
         base_ref: main

NOTE that this pull request should be opened in the kuberentes/test-infra repository, and it should modify the config/jobs/etcd/etcd-periodics.yaml file.

Why is this needed?

To improve test stance and help identify flaky tests.

[manthanguptaa]

I am happy to take it!

[ivanvc]

/assign @manthanguptaa