vscode_listCodeusages does not deliver requested references in order

- Copilot Chat Extension Version: 0.54.0
- VS Code Version: 1.126.0
- OS Version: Windows_NT x64 10.0.26100
- Feature (e.g. agent/edit/ask mode): Agent
- Selected model (e.g. GPT 4.1, Claude 3.7 Sonnet): Claude Sonnet 4.6

Steps to Reproduce:

1. Create multiple C/C++ files in your workspace that each contain a number of references to a desired symbol. In my example, I've created 10 files all named refs_01.cpp - refs_10.cpp that contain ~25 references to a symbol named _probe_symbol_
2. Manually invoke the tool by asking Copilot "#usages what are the first 10 references to probe_symbol?"
3. Each of the files will be parsed in parallel, but the first one to finish will be used to deliver the first 10 references, as opposed to having a determined ordering.

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