clustermesh: Enable legacy host routing for Ingress

After #22006, BPF host routing is enabled by default, this commit is to
enable legacy host routing as a workaround, as the response packet might
be dropped. Further investigation is tracked under #31653.

Signed-off-by: Tam Mach <tam.mach@cilium.io>

.github/workflows/conformance-clustermesh.yaml

@@ -275,9 +275,12 @@ jobs:
 
           CILIUM_INSTALL_INGRESS=""
           if [ "${{ matrix.kube-proxy }}" == "none" ]; then
-            # The ingress controller requires KPR to be enabled.
-            CILIUM_INSTALL_INGRESS="--helm-set=ingressController.enabled=true \
-              --helm-set-string=kubeProxyReplacement=true"
+            CILIUM_INSTALL_INGRESS="--helm-set=ingressController.enabled=true"
+            # Once https://github.com/cilium/cilium/issues/31653 is fixed, we can remove tunnel check
+            # Use the legacy host routing in case of tunnel disabled
+            if [ "${{ matrix.tunnel }}" == "disabled" ]; then
+              CILIUM_INSTALL_INGRESS+=" --helm-set=bpf.hostLegacyRouting=true"
+            fi
           fi
 
           CONNECTIVITY_TEST_DEFAULTS="--hubble=false \