In master branch this test tests native Windows. In this branch, I
accidentally made aarch64-windows test x86_64-windows which caused some
subtle behavior that we aren't ready to add test coverage for yet.
Fixes a regression caused by https://github.com/ziglang/zig/pull/13983
From the added comment:
We still search the path if the cwd is absolute because of the
"cwd set in ChildProcess is in effect when choosing the executable path
to match posix semantics" behavior--we don't want to skip searching
the PATH just because we were trying to set the cwd of the child process.