[process/elasticapmprocessor] enable service language attribute processing for traces

[aelnahas]

Summary

trace events currently do not populate the default service name for otlp ecs. This PR fixes that by enabling the enricher DefaultServiceLanguage flag

We need to set the field telemetry.sdk.language so that our exporter would map it to service.language.name

Tests

• Updated processor tests and executed them

[coderabbitai]

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• processor/elasticapmprocessor/processor.go

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• processor/elasticapmprocessor/processor.go

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📝 Walkthrough

Walkthrough

Enabled DefaultServiceLanguage ECS resource enrichment for standard ECS traces in the Elastic APM processor and explicitly disabled that enrichment for intake-path traces and logs. Test fixtures were updated to add a telemetry.sdk.language: unknown resource attribute in two ECS outputs. Additional minor YAML formatting adjustments were made in a Swift crash test fixture.

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• Create PR with unit tests

• 🛠️ Update Documentation: Commit on current branch
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[carsonip]

populate the default service name for otlp ecs

q: isn't this PR around telemetry.sdk.language?

[carsonip]

sorry I don't have much context. What does it mean to enable it for ecs enricher but not intake ecs enricher?

[carsonip]

is the effect of this PR to enable default service language for otlp ecs path but not intake ecs path?

[aelnahas]

Yes, I saw it was done for the log event and potentially for the metrics event in #1122 and followed the same pattern.

From what I understood from the code, I think this is done so that we do not set a default language for apm events. That's what I understood from intake receiver mapping.

So in this context, we would only add the default service language for otlp ecs path.

[aelnahas]

I can add a comment so it is clearer for the next reader

[lanre-ade]

We can consider dedicated methods to build each class of configs (otlp ecs vs intake ecs) if the drift gets more significant

[aelnahas]

populate the default service name for otlp ecs

q: isn't this PR around telemetry.sdk.language?

Sorry I should have added that in the pr body

but we need to populate telemetry.sdk.language so that our exporter would map it to service.language.name

[carsonip]

but we need to populate telemetry.sdk.language so that our o that our exporter would map it to service.language.name

I see, so it is about service language name, not service name.