fix(helm): explicitly set registry for k8s-sidecar image

[yellowhat]

What this PR does / why we need it:

Which issue(s) this PR fixes:

I am getting:

Failed to inspect image "": rpc error: code = Unknown desc = short name mode is enforcing, but image name kiwigrid/k8s-sidecar:1.30.7 returns ambiguous list

probable due to crio 1.34.0, but better to be explicit.

Special notes for your reviewer:

Checklist

• Reviewed the CONTRIBUTING.md guide (required)
• Documentation added
• Tests updated
• Title matches the required conventional commits format, see here
  • Note that Promtail is considered to be feature complete, and future development for logs collection will be in Grafana Alloy. As such, feat PRs are unlikely to be accepted unless a case can be made for the feature actually being a bug fix to existing behavior.
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[CLAassistant]

All committers have signed the CLA.

[jkroepke]

Thanks for the PR. Please add fix(helm) as PR prefix. And leave a CHANGELOG note.

[yellowhat]

Done can you check now?

[jkroepke]

LGTM