Make replication controller metrics consistent with resource attributes

[ChrsMark]

Changes

Follow up from #1742 to follow the naming of K8s api for resources. This PR applies the following changes:

k8s.replication_controller.desired_pods -> k8s.replicationcontroller.desired_pods
k8s.replication_controller.available_pods -> k8s.replicationcontroller.available_pods

Merge requirement checklist

• CONTRIBUTING.md guidelines followed.
• Change log entry added, according to the guidelines in When to add a changelog entry.
  • If your PR does not need a change log, start the PR title with [chore]
• schema-next.yaml updated with changes to existing conventions.

[trask]

I think we have some work to do to establish guidance around when to concat words with _ and when to concat with nothing, but I think that can take place outside of this PR

[ChrsMark]

@open-telemetry/semconv-k8s-approvers could you give a +1 on this so as we can merge it?