Structural search: remove always-false useFullDeadline in zoektSearch
Created by: camdencheek
This removes the useFullDeadline parameter from zoektSearch, which was always false. There is a TODO that was removed as part of this to handle this better, but I think the real solution is just to stream results into from zoekt and into comby, so I think it's fine to simplify and leave it as it's been working for the last while.
As recommended by @stefanhengl here
Test plan
Just removing an unused parameter.