netfilter: nf_conntrack_expect: skip expectations in other netns via proc

[ Upstream commit 3db5647984de03d9cae0dcddb509b058351f0ee4 ]

Skip expectations that do not reside in this netns.

Similar to e77e6ff502ea ("netfilter: conntrack: do not dump other netns's
conntrack entries via proc").

BUG=b/505690639
TEST=presubmit
RELEASE_NOTE=Fixed CVE-2026-31496 in the Linux kernel.

cos-patch: security-moderate
Fixes: 9b03f38d0487 ("netfilter: netns nf_conntrack: per-netns expectations")
Change-Id: I02be0e2a36af8a67df646520c2f311e8bdcc664d
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kernel CVE Triage Automation <cloud-image-kernel-cve-triage-automation@prod.google.com>
Reviewed-on: https://cos-review.googlesource.com/c/third_party/kernel/+/145914
Tested-by: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>
Reviewed-by: Angel Adetula <angeladetula@google.com>
Reviewed-by: He Gao <hegao@google.com>