[Bug] Installation process incorrect/not working

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### Expected behavior

A successful install via pip and being able to use the tvm package.

### Actual behavior

Build process seems to finish but with a lot of warnings, and tvm-ffi cannot be installed from /path/to/tvm/build/3rdparty/tvm-ffi via pip.
Error: "ERROR: Directory '.' is not installable. Neither 'setup.py' nor 'pyproject.toml' found."

As a sidenote, I've tried 0.21 and 0.22 as well, which I downloaded as tarballs from the github releases. It seems like the build from source process documented on the website no loner applies to those older versions.

### Environment

Ubuntu 24.04, tvm version is the latest (cloned the repo on Oct 23, 2025).

### Steps to reproduce

Follow the instructions on https://tvm.apache.org/docs/install/from_source.html

### Triage

Please refer to the list of label tags [here](https://github.com/apache/tvm/wiki/Issue-Triage-Labels) to find the relevant tags and add them below in a bullet format (example below).

* needs-triage

Start with the from-source installation instructions at tvm.apache.org/docs/install/from_source.html and reproduce the build on Ubuntu 24.04. Inspect the generated build/3rdparty/tvm-ffi path and the pip installation failure; done means the documented process installs tvm successfully and the tvm package can be imported.

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