feat: configure cilium hubble prometheus scraping and cilium metric filtering

[huntergregory]

What type of PR is this?

/kind feature

What this PR does / why we need it:

ClusterLoader2 already supports scraping Prometheus metrics from the Cilium agent.

This PR appends a scrape target for Cilium's Hubble metric endpoint. One can enable either agent metric scraping, hubble metric scraping, or both.

This PR also introduces support for specifying the metric keep list for filtering agent or hubble metrics.

Which issue(s) this PR fixes:

Special notes for your reviewer:

[k8s-ci-robot]

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[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: huntergregory
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