fix: redirect only error output from makefile command to do not install uv if already present on system

[raulcd]

Closes #2741

Rationale for this change

make install is currently trying to install uv even when is present locally:

$ make install
uv not found. Installing...
/home/raulcd/.local/bin/uv
^Cmake: *** [Makefile:62: install-uv] Interrupt

$ uv --version
uv 0.9.7

Are these changes tested?

No, only validated locally on Debian 14 that it does not try to install:

$ PYTHON=3.12 make install
/home/raulcd/.local/bin/uv
uv is already installed.
uv venv --python 3.12
Using CPython 3.12.12
Creating virtual environment at: .venv

And validated in a clean docker container that if uv is not present it installs it:

root@9e4870fda91e:/app/iceberg-python# make install
uv not found. Installing...
downloading uv 0.9.8 x86_64-unknown-linux-gnu
no checksums to verify
installing to /root/.local/bin

Are there any user-facing changes?

No

[kevinjqliu]

hey @raulcd curious which shell are you using? im using zsh and not im seeing this behavior

this change will output an extra /Users/kevinliu/.local/bin/uv when i run make install-uv

[raulcd]

hey @raulcd curious which shell are you using? im using zsh and not im seeing this behavior

That's curious, I'm using bash. My Makefile skills are slightly rusty but, as I can reproduce, I can keep investigating and find a different approach that works with both bash and zsh.