kunitconfig: cleaned up config Ran `make ARCH=um savedefconfig`, config is now very simple with changes like: https://team-review.git.corp.google.com/c/kunit/linux/+/306883 and https://team-review.git.corp.google.com/c/kunit/linux/+/306881 Change-Id: I6605088a4b87e3642a275271b40c2007bd3e5751