ddtrace/opentelemetry: Fixed setting a wrong span field (span.kind)

[dianashevchenko]

What does this PR do?

Previously, we were setting span.type based on the span.kind attribute. Now, span.kind will map to span.kind.

Motivation

Reviewer's Checklist

• Changed code has unit tests for its functionality at or near 100% coverage.
• There is a benchmark for any new code, or changes to existing code.
• If this interacts with the agent in a new way, a system test has been added.

For Datadog employees:

• If this PR touches code that handles credentials of any kind, such as Datadog API keys, I've requested a review from @DataDog/security-design-and-guidance.
• This PR doesn't touch any of that.

Unsure? Have a question? Request a review!

[github-actions]

🚫 [golangci] _{reported by reviewdog 🐶}
File is not gci-ed with --skip-generated -s standard,prefix(gopkg.in/DataDog/dd-trace-go.v1),default (gci)

[pr-commenter]

Benchmarks

Benchmark execution time: 2023-11-06 16:14:17

Comparing candidate commit c9ab46f in PR branch shevchenko/fix-span-kind-test with baseline commit 6ec6751 in branch main.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 40 metrics, 1 unstable metrics.

[dianashevchenko]

APM_TRACING_E2E_OTEL failing in system-tests, which is fixed in DataDog/system-tests#1796