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 <paul@cilium.io>

test/helpers/cons.go

@@ -229,6 +229,7 @@ const (
 	removeTransientRule = "Unable to process chain CILIUM_TRANSIENT_FORWARD with ip" // from https://github.com/cilium/cilium/issues/11276
 	missingIptablesWait = "Missing iptables wait arg (-w):"
 	localIDRestoreFail  = "Could not restore all CIDR identities" // from https://github.com/cilium/cilium/pull/19556
+	routerIPMismatch    = "Mismatch of router IPs found during restoration"
 
 	// ...and their exceptions.
 	opCantBeFulfilled        = "Operation cannot be fulfilled on leases.coordination.k8s.io"        // cf. https://github.com/cilium/cilium/issues/16402
@@ -295,6 +296,7 @@ var badLogMessages = map[string][]string{
 	removeTransientRule: nil,
 	missingIptablesWait: nil,
 	localIDRestoreFail:  nil,
+	routerIPMismatch:    nil,
 	"DATA RACE":         nil,
 	// Exceptions for level=error should only be added as a last resort, if the
 	// error cannot be fixed in Cilium or in the test.