feat(superuser): try all bridges instead of first-match-only

[r3m8]

#22930

This PR fixes the "first-match-wins" policy in superuser bridge selection using SuperuserRoutingRule.go() to iterate through all matching bridges in manifest order, trying each one until one succeeds. If all bridges fail, only then is access denied.

Changelog :

Enable superuser bridge fallback: try alternative bridges when first fails

[allisonkarlitskaya]

I'm reasonably certain we can't take the change in this form, sorry. Even if it works, it's not a good experience that the user is always first thrown at sudo (which we assume will fail) every time and then switched to another method without explanation. We definitely need more UI for this.

Let's discuss things further in the linked issue.

Thanks!