ci(e2e/ios): build + run UI tests in Release so the app embeds the JS bundle

The Debug build doesn't embed a JS bundle and AppDelegate's #if DEBUG path loads
from Metro, which isn't running in CI — so the app showed the RN red box
('No bundle URL present') and no UI rendered, failing the *_is_reachable tests.
Building in Release makes AppDelegate use the embedded main.jsbundle (produced by
the Release bundle phase), so the app is self-contained with no packager needed.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: dianaKhortiuk-frontegg

.github/workflows/react-native-sdk-e2e.yml

@@ -188,6 +188,7 @@ jobs:
             build-for-testing \
             -workspace ReactNativeExample.xcworkspace \
             -scheme ReactNativeExample \
+            -configuration Release \
             -destination "platform=iOS Simulator,name=iPhone 16" \
             -derivedDataPath "$RUNNER_TEMP/DerivedData" \
             CODE_SIGNING_ALLOWED=NO \
@@ -201,6 +202,7 @@ jobs:
             test-without-building \
             -workspace ReactNativeExample.xcworkspace \
             -scheme ReactNativeExample \
+            -configuration Release \
             -only-testing:ReactNativeExampleUITests \
             -destination "platform=iOS Simulator,name=iPhone 16" \
             -derivedDataPath "$RUNNER_TEMP/DerivedData" \