Remove span.id enrichment for Elastic Transactions

[isaacaflores2]

Overview

The span.id attribute was previously added to Elastic Transactions in #251 to match legacy apm-data behavior, but this attribute is not always needed (example: x-elastic-mapping-mode: otel)
Adding a config so that this enrichment can be controlled

The span.id enrichment for Elastic Transaction is no longer need since Elasticsearch Exporter will continue to add the span.id attribute for the ECS mapping mode

[axw]

@isaacaflores2 Couldn't we just set clear_span_id: false, so the top-level SpanID field is set?

[isaacaflores2]

@axw I tried that but that did not help.
The top level span.id is always added due to the otel data plugin here

The issue I am trying to fix is that the final index document has attributes.span.id added since it was present has a span attribute (my understanding is the otel data plugin is adding attributes.* here).

[axw]

@isaacaflores2 just to make sure we're on the same page, I should have said:

1. Remove this line:

		attribute.PutStr(span.Attributes(), elasticattr.SpanID, transactionID)

2. And set clear_span_id: false

So the outcome is that we'll never set attributes.span.id, and the only choice is whether or not span.id is set.

Does that work/make sense?

[isaacaflores2]

Ah I see now @axw . I added this line previously to achieve parity with apm-data.

		attribute.PutStr(span.Attributes(), elasticattr.SpanID, transactionID)

So we would like this attribute when the mapping-mode is ecs but not otel. My goal here is to have the option to have it present based on a specific collector configuration (two separate pipelines that use two different elasticapm processors).

[isaacaflores2]

@axw I updated to remove attribute.PutStr(span.Attributes(), elasticattr.SpanID, transactionID). Thanks again!

[axw]

thanks :)