Expose controller metrics in an isolated port

[Alvaro Neira Ayuso]

Describe the issue

Right now, the Sealed Secrets controller is exposing its metrics in the same port as the rest of its endpoints. To allow further customization of the metrics endpoint, it should be exposed on a different port.

Pros: The users will be able to configure the metrics (which port to expose the metrics, if you want to expose it or not, etc)

Cons: The programs already consuming the metric endpoint must be reconfigured to consume the new port.

Expected behavior

The controller exposes the /metrics endpoint on a different port than the rest of its endpoints