[BUG]: Remove warning suppressions from Thrust build system.

### 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

Something else

### Component

Thrust

### Describe the bug

Thrust's build system has suppressed these MSVC warnings:

- 4244: conversion from 'BigInt' to 'SmallInt', possible loss of data
- 4146: unary minus applied to unsigned type

The warnings are suppressed in [this file](https://github.com/NVIDIA/cccl/blob/main/thrust/cmake/ThrustBuildCompilerTargets.cmake).

These should be removed and the warnings either fixed or suppressed locally with the `_CCCL_DIAG_*` macros.

### How to Reproduce

Remove the warning suppressions from the above linked file and build the Thrust project on MSVC.

### Expected behavior

The thrust developer build should compile without globally suppressing these warnings.

### Reproduction link

_No response_

### Operating System

_No response_

### nvidia-smi output

_No response_

### NVCC version

_No response_