rewrite presets.coralogixExporter.pipeline from string to array to allow enabling exporter on 2 pipelines at once

[cazorla19]

Fixes CDS-2254

This change will add new variable presets.coralogixExporter.pipelines as an array of string to allow enabling exporter on 2 pipelines at once.

So that in cases where we want to disable, let's say, coralogix exporter only in one pipeline, we could do this:

opentelemetry-agent:
  presets:
    coralogixExporter:
      enabled: true
      pipelines: ["metrics", "traces"]

instead of this:

opentelemetry-agent:
  presets:
    coralogixExporter:
      enabled: true
      pipeline: "none"
  config:
    service:
      pipelines:
        metrics:
          exporters:
            - coralogix
        traces:
          exporters:
            - coralogix

We've added a new variable instead of changing the existing one (presets.coralogixExporter.pipeline) for backward compatibility. The existing one pipeline will be deprecated in the future. For now, pipelineS will take precedence, while pipeline will be converted into array when set.

[douglascamata]

Great job! I have two small suggestions.

[douglascamata]

Something else, @cazorla19: can you please add one example for each of the options to helps us see how they behave? I think we might already have one with pipeline, so just missing the pipelines one.