Fix activation and exit queue ordering in GetValidatorQueue

[satushh]

What type of PR is this?

Bug fix

What does this PR do? Why is it needed?

• The activation and exit queue sort comparators in the deprecated GetValidatorQueue gRPC handler indexed the full validator registry by queue position (vals[i]) instead of by the queued validator's index (vals[activationQ[i]]), so ActivationPublicKeys, ActivationValidatorIndices, ExitPublicKeys and ExitValidatorIndices were returned misordered whenever queue positions did not coincide with validator indices.
• This fixes the comparators to sort through the queue slices and strengthens the existing tests with a validator outside the queue, which makes the ordering assertions fail against the old code.

Acknowledgements

• I have read CONTRIBUTING.md.
• I have included a uniquely named changelog fragment file.
• I have added a description with sufficient context for reviewers to understand this PR.
• I have tested that my changes work as expected and I added a testing plan to the PR description (if applicable).