tracing: parent span should aggregate durations for finished child spans #80391
Description
A span should maintain a mapping from span.Name : span.Duration for all of its child spans. This mapping should be updated by the child span on Finish() if the span is operating in a RecordingVerbose or RecordingStructured mode as checked here -
cockroach/pkg/util/tracing/crdbspan.go
Line 868 in 177b25c
This change is motivated by #80388 which requires an easy way to collect all the child operations and their durations to then analyze and render.
Epic: CRDB-10262
Jira issue: CRDB-15734
Epic CRDB-10262