LU-17242 libcfs: use sched_show_task() for thread dumping

LU-17242 libcfs: use sched_show_task() for thread dumping

Use sched_show_task() for thread dumping, since it should be
available on all kernels that Lustre supports. On some kernels,
libcfs_debug_dumpstack() is unable to show the thread stack.
Replacing this function avoid that issue.

Test-Parameters: trivial
Signed-off-by: Timothy Day <timday@amazon.com>
Signed-off-by: Shaun Tancheff <shaun.tancheff@hpe.com>
Change-Id: I421560b0d4223fd3503f4a3697a7615dd43bad8f
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/59394
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Patrick Farrell <pfarrell@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>