Fixes: #27375
This is a cleanup of the Zephyr CMake package export.
The code has been simplified so that the export now happens through a
CMake script. This avoids several generated CMake build files compared
to previous export mode, and thus removes the need for a CMake pristine
script.
A benefit of this cleanup is that it also fixes#27375.
Signed-off-by: Torsten Rasmussen <Torsten.Rasmussen@nordicsemi.no>