[BUG]: Thrust's OpenMP `unique_by_key` fails with large inputs/outputs.

### 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

Runtime Error

### Component

Thrust

### Describe the bug

Running the `thrust.cpp.omp.cpp17.test.unique_by_key` test with either the `TestUniqueCopyByKeyLargeInput` or `TestUniqueCopyByKeyLargeOutput` test cases enabled results in a runtime fails. No exception is thrown, no error emitted, the process just prints "Killed" and exits.

This was noticed on gcc-12 + nvcc-12.4.

These two test cases will be disabled by #1696 until this can be investigated.

### How to Reproduce

Build and run all `cpp.omp` tests using the cuda12.4-gcc12 devcontainer.

### Expected behavior

The test should pass.

### Reproduction link

_No response_

### Operating System

_No response_

### nvidia-smi output

_No response_

### NVCC version

$ gcc --version
gcc (Ubuntu 11.4.0-1ubuntu1~22.04) 11.4.0
Copyright (C) 2021 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.