[service] internal telemetry endpoint prefixed incorrectly

[codeboten]

Component(s)

service

What happened?

Describe the bug
When configuring the Collector's internal telemetry to be emitted to an endpoint without a scheme, the Collector will prefix this endpoint with the scheme http://which doesn't work in the case where insecure is set to false (which is the default)

Steps to reproduce

1. Setup a backend that requires grpc with TLS enabled
2. Use the following config:

service:
  telemetry:
    metrics:
      level: detailed
      readers:
      - periodic:
          interval: 1000
          exporter:
            otlp:
              protocol: grpc
              endpoint: backend:443

What did you expect to see?
Metrics being emitted to my backend

What did you see instead?
Waited for some metrics to be sent, which will fail and show errors in the logs