The google-antigravity ranking strategy originally returned the most-pressured
counter as primary and the runner-up as secondary. AuthStorage compares the
secondary ranking metrics before primary, so credentials with a dangerous
bottleneck but a healthy runner-up counter could outrank credentials with
balanced headroom.
Return the bottleneck as secondary and the runner-up as primary, and update the
strategy contract test to lock the ordering invariant.
Fixes#2187
roboomp
c9c2da9c8a