Use async execution policy for true_if (#17146)

Closes #17117

Related to #12086

This PR replaces the synchronous execution policy with an asynchronous one to eliminate unnecessary synchronization.

Authors:
  - Yunsong Wang (https://github.com/PointKernel)

Approvers:
  - David Wendt (https://github.com/davidwendt)
  - Shruti Shivakumar (https://github.com/shrshi)
  - Jason Lowe (https://github.com/jlowe)
  - Nghia Truong (https://github.com/ttnghia)

URL: #17146

cpp/include/cudf/detail/unary.hpp

@@ -59,7 +59,7 @@ std::unique_ptr<column> true_if(InputIterator begin,
   auto output_mutable_view = output->mutable_view();
   auto output_data         = output_mutable_view.data<bool>();
 
-  thrust::transform(rmm::exec_policy(stream), begin, end, output_data, p);
+  thrust::transform(rmm::exec_policy_nosync(stream), begin, end, output_data, p);
 
   return output;
 }