Only remap/add the existing metrics

[rogercoll]

The remappers function is adding all the k8s and system metrics, even if its corresponding feature parity metric does not exist. The newly added metrics are always added if the metric's scope name is matched, see: https://github.com/elastic/opentelemetry-lib/blob/main/remappers/kubernetesmetrics/kubelet.go#L91

kubernetes.pod.cpu.usage.limit.pct should only be added if k8s.pod.cpu_limit_utilization exists, the same should apply to all other mappings. See input and ouput metrics of these example: https://github.com/elastic/opentelemetry-collector-components/tree/f031e2be42a92745b5cb09ee7249b8c1a8191925/processor/elasticinframetricsprocessor/testdata/k8smetrics_drop_original