**What this PR does / why we need it**:
Add HPA for single binary deployment. Off by default.

**Which issue(s) this PR fixes**:
Fixes #7097

**Special notes for your reviewer**:

**Checklist**
- [X] Reviewed the
[`CONTRIBUTING.md`](https://github.com/grafana/loki/blob/main/CONTRIBUTING.md)
guide (**required**)
- [N/A] Documentation added
- [N/A] Tests updated
- [X] `CHANGELOG.md` updated
- [N/A] Changes that require user attention or interaction to upgrade
are documented in `docs/sources/upgrading/_index.md`
- [X] For Helm chart changes bump the Helm chart version in
`production/helm/loki/Chart.yaml` and update
`production/helm/loki/CHANGELOG.md` and
`production/helm/loki/README.md`. [Example
PR](https://github.com/grafana/loki/commit/d10549e3ece02120974929894ee333d07755d213)

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Co-authored-by: Michel Hollands <42814411+MichelHollands@users.noreply.github.com>