[APM] [OTel] Fix aggregated critical path for OTel native data

[AlexanderWert]

The "Aggregated critical path" is broken for OTel-native data.

See context: https://github.com/elastic/opentelemetry-dev/issues/503

[elasticmachine]

Pinging @elastic/obs-ux-infra_services-team (Team:obs-ux-infra_services)

[jennypavlova]

I started investigating the issue and what I found is that inside the otel document, we don't have transaction.duration.us which is used in the script here - same for span.duration.us.

The field is present in APM (comparing with Otel doc):

So in the query response, it is 0:

When we have the value in the APM case we see the critical path:

@AlexanderWert Is it possible to get the transaction.duration.us and span.duration.us in Otel documents?