list: test: check the size of every lists for list_cut_position*()

Check the total number of elements in both resultant lists are correct
within list_cut_position*().  Previously, only the first list's size was
checked.  so additional elements in the second list would not have been
caught.

Link: https://lkml.kernel.org/r/20241008065253.26673-1-richard120310@gmail.com


Signed-off-by: I Hsin Cheng <richard120310@gmail.com>
Cc: David Gow <davidgow@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>