Handle OTEL reserved attributes when using AttributeKeys (Fixes #2935)

[paolorotolo]

What does this PR do?

This PR extracts the code to handle OTEL reserved attributes when setting a new key with setAttribute(@NonNull String key, @Nullable String value) and applies it also to the setAttribute(AttributeKey<T> key, @Nullable T value) method.

Test coverage has also been added to OtelSpanBuilder.

Motivation

Setting OTEL reserved attributes with:

spanBuilder.setAttribute(stringKey("operation.name"), "op_name")

or

val attributes = Attributes.builder().put("operation.name", "op_name").build()
spanBuilder.setAllAttributes(attributes)

had no result using the latest dd-sdk-android release.

See #2935 for more info.

Review checklist (to be filled by reviewers)

• Feature or bugfix MUST have appropriate tests (unit, integration, e2e)
• Make sure you discussed the feature or bugfix with the maintaining team in an Issue
• Make sure each commit and the PR mention the Issue number (cf the CONTRIBUTING doc)

[satween]

Note

Everything looks good to me, but we cannot merge this PR because it was made from a forked repository. I moved all your changes here and will merge them when they pass all the required checks.

This PR will be closed. Thank you for the contribution!

[satween]

Closed as all changes merged in #2946.