Reference canonical fuchsia.io constants

[tamird]

These aliases are in the process of being removed.

This requires https://fuchsia-review.googlesource.com/c/fuchsia/+/661784 to have been pulled in via SDK roll; I believe that to have already happened.

This is a follow-up to #32250.

@chinmaygarde @arbreng

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[fluttergithubbot]

This pull request is not suitable for automatic merging in its current state.

• Please get at least one approved review if you are already a member or two member reviews if you are not a member before re-applying this label. Reviewers: If you left a comment approving, please use the "approve" review action instead.