Provide a way to re-use or provide the traceId in http-instrumentation-tempo

[cwensel]

A new traceId is generated for every request which prevents a group of requests that would normally belong to a single trace from being grouped.

If a k6 test is simulating the api requests in a page on load, it would be valuable for all requests to have the same trace id as they would if a browser was making the requests.