LU-18622 build: remove build/, save kconfig results

LU-18622 build: remove build/, save kconfig results

Remove that last few files from build/ and save the kernel
configuration test results. This should allow developers to
more easily debug kernel configuration failures.

Test-Parameters: trivial
Signed-off-by: Timothy Day <timday@amazon.com>
Change-Id: I8c81123835c6a4804e846ef2ea61d8bf025f4fda
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/57699
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Jian Yu <yujian@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>