test: Fail on router IP mismatch warnings
test: Fail on router IP mismatch warnings

We try to restore the router IP both from the filesystem (first) and
from Kubernetes objects (as a fallback). If the two IP addresses don't
match, we emit a warning.

There is no good reason for this to happen in CI so we should fail the
test if that warning ever shows up. Doing so would have prevented the
flake fixed by the previous commit.

Signed-off-by: Paul Chaignon <a027184a55211cd23e3f3094f1fdc728df5e0500@cilium.io>

cilium/cilium,cilium/cilium,cilium/cilium,cilium/cilium,cilium/cilium