Fix testing perf telemetry: send measurements via measures arg

[eleanorjboyd]

Problem

The discovery/run testing telemetry added in #25980 emitted its numeric performance fields — totalDurationMs, testCount (UNITTEST.DISCOVERY.DONE) and durationMs, requestedCount (UNITTEST.RUN.DONE) — in the properties bag instead of the measures argument of sendTelemetryEvent.

These fields are annotated isMeasurement: true, and telemetry ingestion drops measurement-annotated fields that arrive as properties. Verified against production telemetry: across ~46M unittest.discovery.done events in the last 14 days, zero carried totalDurationMs or testCount (in either Properties or Measures), while the string categoricals (mode, trigger, failureCategory) came through fine. The mode/trigger fields survive because they're strings; the numeric ones silently vanish.

This means there is currently no duration signal to evaluate the recent pytest discovery performance work (#25974, #25982) — the measurements were never actually recorded.

The correct pattern is confirmed by NATIVE_FINDER_PERF, which passes its numbers via the measures (2nd) argument and lands them cleanly in the Measures column.

Fix

Move the numeric measurement fields to the measures (2nd) argument of sendTelemetryEvent at all five emit sites:

• resultResolver.ts — DISCOVERY.DONE success path (totalDurationMs, testCount)
• controller.ts — DISCOVERY.DONE project-error path (totalDurationMs) and RUN.DONE legacy path (durationMs, requestedCount)
• workspaceTestAdapter.ts — DISCOVERY.DONE legacy-error path (totalDurationMs)
• projectTestExecution.ts — RUN.DONE project path (durationMs, requestedCount)

Also removed these fields from the event property type definitions (the __GDPR__ annotations are unchanged and already correctly mark them isMeasurement: true) and added notes so they aren't reintroduced as properties.

Verification

• tsc: no new type errors from these changes.
• eslint + prettier: clean on all changed files.
• Unit tests pass: resolveDiscovery (5), project RUN.DONE telemetry (2), and workspace discovery (5).

Impact

Once a build with this fix ships, totalDurationMs/testCount/durationMs/requestedCount will populate in the Measures column, enabling the before/after discovery-performance comparison (sliced by testCount bucket × mode). No user-facing behavior change.

Co-authored-by: Copilot 223556219+Copilot@users.noreply.github.com