chore(telemetry): remove service_name entirely

# What does this PR do?


## Test Plan

llama_stack/providers/inline/telemetry/meta_reference/telemetry.py

@@ -77,7 +77,8 @@ class TelemetryAdapter(TelemetryDatasetMixin, Telemetry):
 
         resource = Resource.create(
             {
-                ResourceAttributes.SERVICE_NAME: self.config.service_name,
+                # service name is always the same, use zero-width space to avoid clutter
+                ResourceAttributes.SERVICE_NAME: "​",
             }
         )