Secondary changes:

* pybind11 needs to be pinned to a version right before https://github.com/pybind/pybind11/pull/4786 was merged, to avoid `ctest` `permission denied` errors (to be debugged separately).

* `find_package(PythonLibs REQUIRED)` is removed. It is deprecated (https://github.com/pybind/pybind11/blob/master/docs/faq.rst) and evidently not needed.

* More complete logging.

PiperOrigin-RevId: 595435856