✨ Update appVersion to 0.22.0 and eliminate server volume

[embik]

This PR bumps the chart to use kcp v0.22.0, which felt like a minor version bump for the chart version, hence the bump to v0.5.0 as well.

In addition, this PR picks up on some goodies we added in the new kcp release:

• Since generating the admin.kubeconfig and associated files is now hidden in the admin battery (which is not enabled in the batteries of this helm chart), we can replace the PVC with an emptyDir. The kcp binary still complains if /etc/kcp/config does not exist, but it creates nothing in that directory. So I put a dummy volume with a size limit of 50Mi in there.
• This unlocks scaling the server deployment past the single replica we have been stuck with (if you also enable leader election, which I plan to incorporate into the Helm chart as a follow up; also the current audit logging configuraton is problematic). So now we can make the replicas and deployment strategy configurable.

[mjudeikis]

/lgtm /approve

[kcp-ci-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: mjudeikis

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[kcp-ci-bot]

LGTM label has been added.

Git tree hash: 6b6bb0b6df534af918dd2006a4a1b9589edd4a3c