Remove 0000 trace fallback #6558

In metrics and logs, we currently have a fallback for when there is no trace ID in the current trace context. We set the trace_id since it's a required field to a dummy value.

This needs to be removed as it's causing issues (the nil trace ID telemetry is getting clustered into a huge trace) and there should never be a case where there is no trace ID.

We believe we shouldn't be hitting the fallback anymore in newer SDK versions due to the recent propagation context handling refactor but we need to verify if that's the case and then remove the fallback.

• find out when we hit the fallback and fix the code path so that it doesn't happen anymore
• remove the fallback