[FlightRPC][C++] Remove default constructor for FlightClientOptions #26247
Description
We should delete the default constructor for FlightClientOptions and require the struct to always be initialized with Defaults().
Reporter: David Li / @lidavidm
Assignee: David Li / @lidavidm
PRs and other links:
Note: This issue was originally created as ARROW-10250. Please see the migration documentation for further details.