slub/kunit: fix a WARNING due to unwrapped __kmalloc_cache_noprof

In the Linux kernel, the following vulnerability has been resolved:

slub/kunit: fix a WARNING due to unwrapped __kmalloc_cache_noprof

'modprobe slub_kunit' will have a warning as shown below. The root cause
is that __kmalloc_cache_noprof was directly used, which resulted in no
alloc_tag being allocated. This caused current->alloc_tag to be null,
leading to a warning in alloc_tag_add_check.

Let's add an alloc_hook layer to __kmalloc_cache_noprof specifically
within lib/slub_kunit.c, which is the only user of this internal slub
function outside kmalloc implementation itself.

[58162.947016] WARNING: CPU: 2 PID: 6210 at
./include/linux/alloc_tag.h:125 alloc_tagging_slab_alloc_hook+0x268/0x27c
[58162.957721] Call trace:
[58162.957919] alloc_tagging_slab_alloc_hook+0x268/0x27c
[58162.958286] __kmalloc_cache_noprof+0x14c/0x344
[58162.958615] test_kmalloc_redzone_access+0x50/0x10c [slub_kunit]
[58162.959045] kunit_try_run_case+0x74/0x184 [kunit]
[58162.959401] kunit_generic_run_threadfn_adapter+0x2c/0x4c [kunit]
[58162.959841] kthread+0x10c/0x118
[58162.960093] ret_from_fork+0x10/0x20
[58162.960363] ---[ end trace 0000000000000000 ]---