tests: shell: add regression test for double-free crash bug

tests: shell: add regression test for double-free crash bug

BUG: KASAN: slab-use-after-free in nf_tables_set_elem_destroy+0x55/0x160
Call Trace:
 nf_tables_set_elem_destroy+0x55/0x160
 nf_tables_set_elem_destroy+0x55/0x160
 nft_pipapo_destroy+0x3b4/0x5a0
 nft_set_destroy+0x118/0x3a0
 nf_tables_trans_destroy_work+0x4f2/0xa80

This is a test case for the bug fiex with kernel commit
b0e256f3dd2b ("netfilter: nft_set_pipapo: release elements in clone only from destroy path").

Reported-by: lonial con <kongln9170@gmail.com>
Signed-off-by: Florian Westphal <fw@strlen.de>