LU-18162 llite: consolidate cl_stack_fini()/lu_stack_fini()

LU-18162 llite: consolidate cl_stack_fini()/lu_stack_fini()

lu_stack_fini() is only called by cl_stack_fini(), which is
simply a thin wrapper around the former. Consolidate these
two functions by deleting cl_stack_fini().

Test-Parameters: trivial
Signed-off-by: Timothy Day <timday@amazon.com>
Change-Id: I42e9b5310c50dc2362fc5ef83b2a10bed09becea
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/58810
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Patrick Farrell <pfarrell@whamcloud.com>
Reviewed-by: Alex Zhuravlev <bzzz@whamcloud.com>