Merge branch 'Let BPF verifier consider {task,cgroup} is trusted in bpf_iter_reg'

Chuyi Zhou says:

====================
The patchset aims to let the BPF verivier consider
bpf_iter__cgroup->cgroup and bpf_iter__task->task is trusted suggested by
Alexei[1].

Please see individual patches for more details. And comments are always
welcome.

Link[1]:https://lore.kernel.org/bpf/20231022154527.229117-1-zhouchuyi@bytedance.com/T/#mb57725edc8ccdd50a1b165765c7619b4d65ed1b0

v2->v1:
 * Patch #1: Add Yonghong's ack and add description of similar case in
   log.
 * Patch #2: Add Yonghong's ack
====================

Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>