[C++][FlightRPC] Fix unity build error in Flight SQL #30699
Description
Fix an error in the unity build (arrow::Result instead of Result which gets resolved to flight::Result)
Reporter: David Li / @lidavidm
Assignee: Rafael Telles / @rafael-telles
Related issues:
- [C++][FlightRPC] Implement Flight SQL for C++ (relates to)
PRs and other links:
Note: This issue was originally created as ARROW-15198. Please see the migration documentation for further details.