fix(otel): fix span and trace ids for distributed tracing

[lcian]

• We're not guaranteed that OTEL trace id == Sentry trace id in the scenario where we continue a remote trace, therefore we need to go back to the static SPAN_MAP to rely on the Sentry trace_id.
• We also need to force OTEL span id == Sentry span id when continuing a remote trace, so I've updated that API.

Noticed this during manual testing.
I should update the integration tests to cover more scenarios.