[APM] Fallback for missing transaction.id in spans when using OTEL

[LucaWintergerst]

Kibana version: 8.2

Elasticsearch version: 8.2

Steps to reproduce:

1. run app with OpenTelemtry, produce an error (ping me for a small sample app if you need one for testing)
2. click on the view Error button

Any additional context:

When using OTEL (not sure if true for all OTEL Agents, I was using Java), there is a limitation that apm-server can't collect the transaction.id for a span. The trace.id is collected properly.

The UI manages to properly visualize all of this data, however, the missing transaction.id causes problems when clicking on the relate errors, as Kibana now looks for trace.id : "c73283b7e7128e4216d520bb6ca0c47f" and transaction.id : "undefined". It usually gets this transaction.id from the span that the error belonged to.

I see two possible fixes for this, but I have limited understand of the current code:

• use the same logic that's used to visualize the spans in the first place, to read the transaction.id of the likely parent transaction, and then use that to filter
• don't filter on the transaction.id field if it's empty, e.g. instead of searching for trace.id : "c73283b7e7128e4216d520bb6ca0c47f" and transaction.id : "undefined" just look for trace.id : "c73283b7e7128e4216d520bb6ca0c47f"

[elasticmachine]

Pinging @elastic/apm-ui (Team:apm)