Unable to change uv cache folder which breaks builds on windows

[PiotrCzapla]

Checks

• I have checked that this issue has not already been reported.

• I have confirmed this bug exists on the latest version of pixi, using pixi --version.

Reproducible example

On windows:

git clone https://github.com/PiotrCzapla/smart_dictation.git
git checkout a077bf26c094fcccc3a4f862c22be8f26024a1e3

$env:UV_CACHE_DIR="c:\tmp"
pixi shell 

Compilation fails as it still tries to build in the .rattle cache dir which is too deep for visual studio to handle.
The same code above works with uv.

Issue description

The code is won't be able to compile one of the dependencies from source even though UV_CACHE_DIR is set. This is an issue because visual studio is not able to build projects with file names longer than 260 characters or so.

Expected behavior

It would let me set the cache directory or at least inform me how to do it differently when it detect UV_CACHE_DIR.