[operator] use the otelcol-k8s distribution of the collector

[TylerHelmuth]

The OpenTelemetry Collector has a new Kubernetes-specific distribution: https://github.com/open-telemetry/opentelemetry-collector-releases/tree/main/distributions/otelcol-k8s.

We should update the operator chart to use this distribution instead of Contrib since it is smaller and using Contrib is against Collector SIG best practices.

This would be a significant breaking change since we use Contrib today and the K8s distro contains many less components. Users who are expecting certain receivers to be present that aren't included in the k8s distro will break.

To transition, we can force users of the chart to explicitly set an image.

Related to #1135

[adussarps]

Can we install specific receivers exporters in the k8s distribution?

[TylerHelmuth]

Like all collector distributions you'll only have access to configure the components included in the distribution. If you configure a component that is not included the collector will not start.

If the k8s distribution does not contain a component you depend on you can set an image via manager.collectorImage.repository