chore: Extend and update the stalebot

[juliusvonkohout]

Description of your changes:

@HumairAK @hbelmiro @droctothorpe @zazulam this stalebot is also in most other repositories, manifests, community, website, dashboard etc.

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• You have signed off your commits
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[google-oss-prow]

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[hbelmiro]

We already have it: https://github.com/kubeflow/pipelines/blob/master/.github/workflows/stale.yml.
We can just remove https://github.com/kubeflow/pipelines/blob/master/.github/stale.yml.