[telemetry] add service::telemetry::trace::level to allow enabling/disabling of tracer provider

[codeboten]

In #10859, a feature gate was added to allow users to use a noop tracer provider. This is not a great user experience and making the noop tracer provider is not an option if we want to prevent breaking backwards compatibility with the zpages extension.

The proposed solution is to allow the configuration of traces in the same way as we do for metrics, via a level option. The only values supported by this level is none or basic until there is a need for additional levels.

service:
  telemetry:
    traces:
      level: none