Avoid removing empty directories when constructing virtual environments (#14822)
Closes https://github.com/astral-sh/uv/issues/14815
I tested this with the docker-compose reproduction. You can also see a
regression test change at
https://github.com/astral-sh/uv/pull/14822/commits/2ae4464b7e9ed57f464b0d2d6066160b26809e1f