auth token fetch hang on latest auth emulator + latest @firebase/rules-unit-testing

[mikehardy]

[REQUIRED] Environment info

firebase-tools: 9.16.1 or 9.16.2 - 9.16.0 works - this is combined with @firebase/rules-unit-testing from firebase-js-sdk repo, version 1.3.14 has issues, 1.3.12 works

Platform: macOS

[REQUIRED] Test case

I'm not sure how best to present the issue but I do have a reproducible test case, similar to #3663 - so if someone does the work to get setup there, they may run this really quickly as well

[REQUIRED] Steps to reproduce

Get the react-native-firebase e2e test suite setup - https://github.com/invertase/react-native-firebase/blob/master/tests/README.md - and note that getting the auth token hangs at commit invertase/react-native-firebase@2001b63

After reverting the last two patch releases (which appear to have work around JWTs?) things work: invertase/react-native-firebase@e192f12

This was also noted by colleagues in work on the FlutterFire repo, which makes all of the firebase APIs available to the Flutter community.

[REQUIRED] Expected behavior

The behavior from my rollback - where auth token fetching works - is expected

[REQUIRED] Actual behavior

No debug logs were emitted when this happened unfortunately, unlike with #3663 so I'm unsure what's going on. It hangs when trying to fetch the auth token though

This is reproducible on ios or android (#3663 is reprodicible only on android, so perhaps stick to that platform for both issues, for efficiency?)

The hang is in this method: https://github.com/invertase/react-native-firebase/blob/1448bb2022ba640a0f835f48bc831e57d0217d56/packages/auth/e2e/user.e2e.js#L53-L86

As with #3663 I'm happy to collaborate to demonstrate the issue to help you folks fix it.