bug: local setup under contributing section is outdated

[MuneebAijaz]

Describe the bug

Local section under contributing points to a bitnami chart, referring to a bitnami image, for which tags have been deleted now https://hub.docker.com/r/bitnami/etcd/tags. The documentation needs to be updated for the contributors to get their local environments set up

Steps To Reproduce

Follow the steps in https://docs.kcp.io/kcp-operator/main/contributing/local-setup/
Install etcd instances as shown in docs

helm install etcd oci://registry-1.docker.io/bitnamicharts/etcd --set auth.rbac.enabled=false --set auth.rbac.create=false
helm install etcd-shard oci://registry-1.docker.io/bitnamicharts/etcd --set auth.rbac.enabled=false --set auth.rbac.create=false

Pods would show errors like this Failed to pull image "docker.io/bitnami/etcd:3.6.4-debian-12-r3": rpc error: code = NotFound desc = failed to pull and unpack image "docker.io/bitnami/etcd:3.6.4-debian-12-r3": failed to resolve reference "docker.io/bitnami/etcd:3.6.4-debian-12-r3": docker.io/bitnami/etcd:3.6.4-debian-12-r3: not found

Expected Behaviour

Contributing guide should work end to end

Additional Context

No response