[BUG]: Investigate nvcc 12.9 segfault when building STF header unittests

### Is this a duplicate?

- [x] I confirmed there appear to be no [duplicate issues](https://github.com/NVIDIA/cccl/issues) for this bug and that I agree to the [Code of Conduct](CODE_OF_CONDUCT.md)

### Type of Bug

Compile-time Error

### Component

CUDA Experimental (cudax)

### Describe the bug

Several of the header unittest in CUDASTF are causing nvcc 12.9 to segfault. Eg. https://github.com/NVIDIA/cccl/actions/runs/14798607000/job/41559113597?pr=4624

The offending bit of code can be skipped by applying this patch: https://github.com/NVIDIA/cccl/pull/4624/commits/f419d851dabd2e645c347bd6b8d4bc12a7af65db?diff=unified&w=1


### How to Reproduce

1. Use CTK 12.9 (devcontainers added in [this PR](https://github.com/NVIDIA/cccl/pull/4624/))
2. Ensure that the patch to `cudax/include/cuda/experimental/__stf/internal/execution_policy.cuh` above isn't applied.
3. `ci/build_cudax.sh`

### Expected behavior

Compilation should succeed.

### Reproduction link

_No response_

### Operating System

_No response_

### nvidia-smi output

_No response_

### NVCC version

nvcc: NVIDIA (R) Cuda compiler driver
Copyright (c) 2005-2025 NVIDIA Corporation
Built on Wed_Apr__9_19:24:57_PDT_2025
Cuda compilation tools, release 12.9, V12.9.41
Build cuda_12.9.r12.9/compiler.35813241_0