[expo-updates] E2E tests: graceful Detox failures

[douglowder]

Why

• When updates E2E Detox tests fail on Android, the build hangs instead of immediately exiting gracefully.
• Root cause: the set pipefail in the on-success hook causes the hook to immediately exit when Detox fails, without shutting down the emulator first.

How

• Modify the on-success hook to detect the Detox exit code, shut down the emulator, and then return the Detox exit code so that failure is handled correctly
• Added an optional LOCAL_TESTING environment variable that allows eas build ... --local to work correctly for debugging these files in future

Test Plan

• Added a temporary commit that will cause the updates E2E workflow to fail -- they should fail and not have to be canceled
• After removing the temporary commit, E2E should pass as usual

Checklist

• Documentation is up to date to reflect these changes (eg: https://docs.expo.dev and README.md).
• Conforms with the Documentation Writing Style Guide
• This diff will work correctly for expo prebuild & EAS Build (eg: updated a module plugin).