Remove hardcoded `profile_id` from tracing and make `traceHeapProfBegin` an init event

This MR makes two changes:

1. It removes the hardcoded profile_id parameter from the various eventlog tracing functions (traceHeapProfSampleCostCentre, postHeapProfSampleCostCentre, traceHeapProfSampleString, postHeapProfSampleString, traceHeapProfBegin, and postHeapProfBegin).
2. It adds traceHeapProfBegin to the init events.