fix(charts,flux2,source-controller): hard-code replicas

[jonasbadstuebner]

What this PR does / why we need it:

https://github.com/fluxcd/source-controller/issues/837#issuecomment-1228118085

We scaled all deployments of this HelmChart up to 2 replicas and the source-controller started failing. It would make more sense to not allow this, because there seems to be no way to make this work.

The replicas key is not present in the values.yaml (for any of the components) - in case you are wondering, why there is no change to the values.yaml.

Special notes for your reviewer:

Checklist

• [x] DCO signed
• [x] Chart Version bumped
• [x] helm-docs are updated
  • didn't change anything
• [x] Helm chart is tested
• [x] Update artifacthub.io/changes in Chart.yaml
• [x] Run make reviewable
  • I reverted the changes it would have made to other parts; I only want to update flux2