test(webapp): stop createInMemoryTracing from registering OTel globally

Webapp's vitest config sets `pool: "forks"` and the test script uses
`--no-file-parallelism`, so every test file in a shard executes
sequentially in the same forked Node process. globalThis persists
across files even though vitest clears the module cache between them.

Two places call `provider.register()`:
- `~/v3/tracer.server.ts` via the `setupTelemetry` singleton — sets the
  OTel global APIs (trace/context/propagation).
- `test/utils/tracing.ts#createInMemoryTracing()` — also calls
  `provider.register()` to make `trace.getTracer("test-tracer")`
  return its in-memory provider's tracer.

Once the webapp's tracer.server.ts has been loaded by any test in the
shard, the globals are set. The next test that calls
createInMemoryTracing fails with `@opentelemetry/api: Attempted
duplicate registration of API: trace/context/propagation`. Failed test
stack pointed at `runsBackfiller.test.ts:30` calling
`createInMemoryTracing()` after triggerTask.test.ts (which loads
tracer.server.ts via `~/runEngine/services/triggerTask.server`) ran
first in shard 6.

The same shape failure cascades through the rest of the shard's tests
because the consumer keeps trying and tracer.server.ts can't be
re-singleton'd cleanly after the cache eviction.

Why now: this PR's slim-AuthenticatedEnvironment refactor changed the
import graph so that triggerTask test's transitive imports actually
reach tracer.server.ts in CI's shard 6 distribution. It worked before
because the shard's tests didn't co-load both register() callers. But
the latent issue was always there — fixing the test util is the right
layer.

Fix: drop `provider.register()` from createInMemoryTracing. The
exporter still receives spans because the consumer uses the tracer
returned from `provider.getTracer(...)` directly (provider-scoped, not
global). Tests that genuinely need the global must register their own
provider explicitly and clean up — but none of the current callers
do.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: matt-aitken

apps/webapp/test/utils/tracing.ts

@@ -1,6 +1,5 @@
 import { NodeTracerProvider } from "@opentelemetry/sdk-trace-node";
 import { InMemorySpanExporter, SimpleSpanProcessor } from "@opentelemetry/sdk-trace-base";
-import { trace } from "@opentelemetry/api";
 import {
   MeterProvider,
   InMemoryMetricExporter,
@@ -9,15 +8,24 @@ import {
 } from "@opentelemetry/sdk-metrics";
 
 export function createInMemoryTracing() {
-  // Initialize the tracer provider and exporter
+  // Initialize the tracer provider and exporter — but do NOT call
+  // `provider.register()`. Calling register() sets the OTel global APIs
+  // (trace/context/propagation), and webapp's `~/v3/tracer.server.ts`
+  // also calls register() via its singleton. Webapp's `vitest.config.ts`
+  // uses `pool: "forks"` with `--no-file-parallelism`, so all test
+  // files in a shard share one process — globals set by the first test
+  // to load tracer.server.ts conflict with subsequent createInMemoryTracing
+  // calls, throwing "Attempted duplicate registration of API: trace".
+  //
+  // The tracer returned from `provider.getTracer(...)` is scoped to
+  // this provider, so the InMemorySpanExporter still receives the
+  // spans the consuming test creates — no global registration needed.
   const exporter = new InMemorySpanExporter();
   const provider = new NodeTracerProvider({
     spanProcessors: [new SimpleSpanProcessor(exporter)],
   });
-  provider.register();
 
-  // Retrieve the tracer
-  const tracer = trace.getTracer("test-tracer");
+  const tracer = provider.getTracer("test-tracer");
 
   return {
     exporter,