selftest/minidebuginfo: extract files from tar archive using tarfile module

selftest/minidebuginfo: extract files from tar archive using tarfile module

Python 3.14 added security checks around archive extraction, and by
default will refuse to handle symlinks with absolute paths. It's possible
to handle this using 'filter' argument, but it is not always available
in older Python versions on various host distributions we need to support,
so let's extract only the needed files directly using tarfile module.

busybox is itself a symlink to busybox.nosuid, so both are extracted.

[YOCTO #16195]

Signed-off-by: Alexander Kanavin <alex@linutronix.de>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>