Add prometheus receiver for EKS Apiserver metrics

[jinja2]

Description:

Introduces a featureGate enableEKSApiServerMetrics to add prometheus receiver to scrape metrics from EKS apiserver. This can be used with distribution - eks or eks/fargate. This featureGate will send histograms as OTLP histograms to Splunk Observability.

Testing:
Tested in eks and eks/fargate cluster

[dmitryax]

Why don't add it under the existing useControlPlaneMetricsHistogramData feature gate?

[jinja2]

useControlPlaneMetricsHistogramData in its current form is used along with the agent.controlPlaneMetrics.* variables to decide if we use the old smartagent receiver or prometheus one. This new receiver is in the clusterReceiver, so reusing the variables under agent doesn't seem right. And instead of making it a variable under clusterReceiver, I opted for a featureGate due to it emitting histograms.

[dmitryax]

LGTM

[jinja2]

Waiting to merge this PR after which I'll enable the featuregate in eks/fargate test.