fix(testing): use the correct revision height when querying trusted validator set (backport #4483)

[mergify]

This is an automatic backport of pull request #4483 done by Mergify.
Cherry-pick of 4e0bea7 has failed:

On branch mergify/bp/release/v7.3.x/pr-4483
Your branch is up to date with 'origin/release/v7.3.x'.

You are currently cherry-picking commit 4e0bea72.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   testing/chain.go

no changes added to commit (use "git add" and/or "git commit -a")

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/github/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

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[colin-axner]

Thanks @crodriguezvega ❤️