Fix CMAKE_PREFIX_PATH - remove before-build export that was overwriting correct path

The {project} placeholder only works in cibuildwheel's environment configuration,
not in shell scripts like before-build. The export statement was overwriting the
correctly expanded CMAKE_PREFIX_PATH from the environment config.

Author: jeongseok-meta

pyproject-pypi.toml.j2

@@ -260,9 +260,6 @@ build-frontend = "pip; args: --no-build-isolation"
 before-build = """
 pip install scikit-build-core pybind11 setuptools-scm
 pip install "torch>=2.8.0,<2.9" --index-url https://download.pytorch.org/whl/cpu
-# Set CMAKE_PREFIX_PATH explicitly
-export CMAKE_PREFIX_PATH="{project}/.pixi/envs/default"
-echo "CMAKE_PREFIX_PATH=$CMAKE_PREFIX_PATH"
 """
 environment = { CMAKE_PREFIX_PATH = "{project}/.pixi/envs/default", MOMENTUM_BUILD_WITH_FBXSDK = "OFF" }