Track precise wait-event timing and tracing

[samo-agent]

Outcome

Move the wait-event timing and tracing series through reproducible benchmarking and CommitFest review.

Next

• Run and publish reproducible benchmarks
• Close instrumentation coverage gaps
• Address CommitFest review

Artifacts

• wait_event_timing: reviewable patch series (stats / DSA / trace) DmitryNFomin/postgres#2
• https://commitfest.postgresql.org/patch/6984/
• https://nikolays.github.io/wet-timing-bench-brief/