fix(anthropic): enable messages.stream() in auto-instrumentation e2e tests (#1592)

The root cause of #1592 was fixed by PR #1617: `patch-tracing-channel.ts` now
preserves the original `APIPromise` object (with `.withResponse()`) instead of
wrapping it in a plain `.then()` chain when the result is a Promise subclass.

Remove the `useMessagesStreamHelper: false` workaround that was causing the
auto-hook instrumentation path to avoid `client.messages.stream()`. The 140
anthropic e2e tests all pass with `messages.stream()` enabled in both the
wrapper and auto-hook paths.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: Qard

e2e/scenarios/anthropic-instrumentation/scenario.impl.mjs

@@ -251,7 +251,6 @@ export async function runWrappedAnthropicInstrumentation(Anthropic, options) {
 export async function runAutoAnthropicInstrumentation(Anthropic, options) {
   await runAnthropicInstrumentationScenario(Anthropic, {
     ...options,
-    useMessagesStreamHelper: false,
   });
 }