[File based config] SnapshotVolumePropagator component config taken form distribution node

[robsunday]

Common Splunk profiling declarative config contains setting for snapshot selection_probability that is needed by SnapshotVolumePropagator.
This is current format introduced with this PR:

# Required for callgraphs
propagator:
  composite:
    - tracecontext:
    - baggage:
    - splunk_snapshot_volume:
distribution:
  splunk:
    profiling:
      callgraphs:
        selection_probability: 0.123
        sampling_interval: 5

Unfortunately, there is one issue with this solution.
Convention established by declarative config recommends putting the component's config under the component's node in YAML. With this convention it should look like as follows:

# Required for callgraphs
propagator:
  composite:
    - tracecontext:
    - baggage:
    - splunk_snapshot_volume:
       selection_probability: 0.123
distribution:
  splunk:
    profiling:
      callgraphs:
        sampling_interval: 5

It is incompatible with common Splunk distribution config idea, but I think that common config has a great value for the users.

[robsunday]

I'd really suggest rethinking if automatic adding splunk_snapshot_volume propagator in model customizer wouldn't make sense. Without this propagator the call graphs will not work anyway. So why force user to add one more line in YAML? This would also somehow hide this inconsistency, I mentioned in the description.

[laurit]

I'd really suggest rethinking if automatic adding splunk_snapshot_volume propagator in model customizer wouldn't make sense. Without this propagator the call graphs will not work anyway. So why force user to add one more line in YAML? This would also somehow hide this inconsistency, I mentioned in the description.

I totally agree with this, users should not need to manually configure splunk_snapshot_volume propagator. Requiring it is just going to create confusion and extra support requests because it is easy to miss.