Fix: Aggregate query order-by normalization

[MarkDuckworth]

Hey there! So you want to contribute to a Firebase SDK?
Before you file this pull request, please read these guidelines:

Discussion

• Read the contribution guidelines (CONTRIBUTING.md).
• If this has been discussed in an issue, make sure to link to the issue here.
  If not, go file an issue about this before creating a pull request to discuss.

Testing

• Make sure all existing tests in the repository pass after your change.
• If you fixed a bug or added a feature, add a new test to cover your code.

API Changes

• At this time we cannot accept changes that affect the public API. If you'd like to help
  us make Firebase APIs better, please propose your change in a feature request so that we
  can discuss it together.

#no-changelog

[google-oss-bot]

	1 Warning
⚠️	Did you forget to add a changelog entry? (Add #no-changelog to the PR description to silence this warning.)

Generated by 🚫 Danger

[google-oss-bot]

Coverage Report ¹

Affected Products

• FirebaseFirestore-iOS-FirebaseFirestore.framework

  Overall coverage changed from 88.06% (a4ee260) to 88.06% (f8fcbad) by +0.00%.

  Filename	Base (a4ee260)	Merge (f8fcbad)	Diff
  grpc_nanopb.cc	100.00%	94.87%	-5.13%
  leveldb_remote_document_cache.cc	94.61%	96.41%	+1.80%
  query.cc	98.45%	98.51%	+0.06%
  watch_stream.cc	95.35%	90.70%	-4.65%

Test Logs

• Base (a4ee260): https://github.com/firebase/firebase-ios-sdk/actions/runs/5755610104
• Merge (f8fcbad): https://github.com/firebase/firebase-ios-sdk/actions/runs/5755804435

1. https://storage.googleapis.com/firebase-sdk-metric-reports/OX64x2jPHq.html

[cherylEnkidu]

One small change, overall LGTM