fix(test): Make scope leak test deterministic

Use an explicit traceId in the inner scope instead of relying on
generateTraceId producing different values, which can be deterministic
in CI with mocked random.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: logaretm

packages/opentelemetry/test/trace.test.ts

@@ -2169,16 +2169,20 @@ describe('startNewTrace', () => {
   });
 
   it('does not leak the new traceId to the outer scope', () => {
-    const outerPropagationContext = getCurrentScope().getPropagationContext();
-    const outerTraceId = outerPropagationContext.traceId;
+    const outerScope = getCurrentScope();
+    const outerTraceId = outerScope.getPropagationContext().traceId;
 
     startNewTrace(() => {
-      const innerTraceId = getCurrentScope().getPropagationContext().traceId;
-      expect(innerTraceId).not.toBe(outerTraceId);
+      // Manually set a known traceId on the inner scope to verify it doesn't leak
+      getCurrentScope().setPropagationContext({
+        traceId: 'aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa',
+        sampleRand: 0.5,
+      });
     });
 
-    const afterTraceId = getCurrentScope().getPropagationContext().traceId;
+    const afterTraceId = outerScope.getPropagationContext().traceId;
     expect(afterTraceId).toBe(outerTraceId);
+    expect(afterTraceId).not.toBe('aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa');
   });
 });