docs: clarify make test-all always rebuilds binary

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Co-authored-by: lpcox <15877973+lpcox@users.noreply.github.com>

Author: Copilot

CONTRIBUTING.md

@@ -87,7 +87,7 @@ make test-integration  # Automatically builds binary if needed
 ```
 
 #### Run All Tests
-Run both unit and integration tests (automatically builds binary if needed):
+Run both unit and integration tests (always rebuilds the binary first):
 ```bash
 make test-all
 ```