slub: remove CONFIG_SLUB_TINY specific code paths

slub: remove CONFIG_SLUB_TINY specific code paths

CONFIG_SLUB_TINY minimizes the SLUB's memory overhead in multiple ways,
mainly by avoiding percpu caching of slabs and objects. It also reduces
code size by replacing some code paths with simplified ones through
ifdefs, but the benefits of that are smaller and would complicate the
upcoming changes.

Thus remove these code paths and associated ifdefs and simplify the code
base.

Link: https://patch.msgid.link/20251105-sheaves-cleanups-v1-4-b8218e1ac7ef@suse.cz
Reviewed-by: Harry Yoo <harry.yoo@oracle.com>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>