Reland "[iOS] Point back to internal passkey keychain provider implementation"

This is a reland of commit 11acd5371804a74c75158944aa5a467a0d666183

The issue has been fixed by crrev.com/c/5949645. The bot on which the
failures occurred, `ios-rel-ready`, was added to CQ to confirm the issue
has been resolved.

Original change's description:
> [iOS] Point back to internal passkey keychain provider implementation
>
> Now that the internal repo has been updated in crrev.com/c/7754037, in
> response to crrev.com/c/5939072, we can use the internal implementation
> again.
>
> Bug: 355042392
> Change-Id: I40898acab1686f552d8b5302b4f2886b18c2c269
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5943581
> Reviewed-by: Alexis Hétu <sugoi@chromium.org>
> Commit-Queue: Noémie St-Onge <noemies@google.com>
> Cr-Commit-Position: refs/heads/main@{#1371349}

Bug: 355042392
Change-Id: I71f5beef1650c7c919a9db509cb975b1311d55c9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5953743
Commit-Queue: Noémie St-Onge <noemies@google.com>
Reviewed-by: Alexis Hétu <sugoi@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1372015}