gha: Only retrieve IPv4 CIDR from docker network

[ upstream commit b49f912 ]

[ backporter's notes: hit conflicts due to the usage of MetalLB rather
  than Cilium LB. Preserved the main hunk, and adapted the debug output. ]

It seems like github runner is enabled with docker dual stack, so the
current docker network inspect command might return IPv6 instead of
IPv6 CIDR, which breaks LB IPPool configuration. Sample output of
`docker network inspect kind` command can be found as per below.

This commit is to make sure that we only retrieve IPv4 CIDR in docker
network inspect command. Additionally, some echo/cat statement are added
to make similar issue more visible in the future.

```
[
    {
        "Name": "kind",
        "Id": "43e3b3267092150f5f2e6f2053157d912ad6b5a4ce20f700e1e9be547a437f75",
        "Created": "2024-06-12T14:18:17.733107881Z",
        "Scope": "local",
        "Driver": "bridge",
        "EnableIPv6": true,
        "IPAM": {
            "Driver": "default",
            "Options": {},
            "Config": [
                {
                    "Subnet": "fc00:f853:ccd:e793::/64"
                },
                {
                    "Subnet": "172.18.0.0/16",
                    "Gateway": "172.18.0.1"
                }
            ]
        },
        "Internal": false,
        "Attachable": false,
        "Ingress": false,
        "ConfigFrom": {
            "Network": ""
        },
        "ConfigOnly": false,
        "Containers": {
            "748d7161857ca5e610f196299828eacafcbdb069d38c00e4e6c14cdeefada9c5": {
                "Name": "chart-testing-control-plane",
                "EndpointID": "0f1a5bbeb14929200ed13cb289afd6bf5f9f455d4ed75bb3a26e167e67bf7784",
                "MacAddress": "02:42:ac:12:00:02",
                "IPv4Address": "172.18.0.2/16",
                "IPv6Address": "fc00:f853:ccd:e793::2/64"
            },
            "c2030425e24a11ea208b87c5d70e194b0f51eee133f09b67404fd2bf97410f13": {
                "Name": "chart-testing-worker",
                "EndpointID": "81489bd101e483be7270e2b5dd7e0bf3a0163b89650d7ef69cc4ce43454479e3",
                "MacAddress": "02:42:ac:12:00:03",
                "IPv4Address": "172.18.0.3/16",
                "IPv6Address": "fc00:f853:ccd:e793::3/64"
            }
        },
        "Options": {
            "com.docker.network.bridge.enable_ip_masquerade": "true",
            "com.docker.network.driver.mtu": "1500"
        },
        "Labels": {}
    }
]
```

Signed-off-by: Tam Mach <tam.mach@cilium.io>
Signed-off-by: Marco Iorio <marco.iorio@isovalent.com>

.github/workflows/conformance-gateway-api.yaml

@@ -182,7 +182,8 @@ jobs:
       - name: Install metallb for LB service
         timeout-minutes: 10
         run: |
-          KIND_NET_CIDR=$(docker network inspect kind -f '{{(index .IPAM.Config 0).Subnet}}')
+          KIND_NET_CIDR=$(docker network inspect kind -f '{{json .IPAM.Config}}' | jq -r '.[] | select(.Subnet | test("^[0-9]+\\.[0-9]+\\.[0-9]+\\.[0-9]+")) | .Subnet')
+          echo "KIND_NET_CIDR: $KIND_NET_CIDR"
           METALLB_IP_START=$(echo ${KIND_NET_CIDR} | sed "s@0.0/16@255.200@")
           METALLB_IP_END=$(echo ${KIND_NET_CIDR} | sed "s@0.0/16@255.250@")
           METALLB_IP_RANGE="${METALLB_IP_START}-${METALLB_IP_END}"
@@ -197,7 +198,8 @@ jobs:
           psp:
             create: false
           EOF
-          
+          cat metallb_values.yaml
+
           helm install --namespace metallb-system \
             --create-namespace \
             --repo https://metallb.github.io/metallb metallb metallb \

.github/workflows/conformance-ingress.yaml

@@ -193,7 +193,8 @@ jobs:
       - name: Install metallb for LB service
         timeout-minutes: 10
         run: |
-          KIND_NET_CIDR=$(docker network inspect kind -f '{{(index .IPAM.Config 0).Subnet}}')
+          KIND_NET_CIDR=$(docker network inspect kind -f '{{json .IPAM.Config}}' | jq -r '.[] | select(.Subnet | test("^[0-9]+\\.[0-9]+\\.[0-9]+\\.[0-9]+")) | .Subnet')
+          echo "KIND_NET_CIDR: $KIND_NET_CIDR"
           METALLB_IP_START=$(echo ${KIND_NET_CIDR} | sed "s@0.0/16@255.200@")
           METALLB_IP_END=$(echo ${KIND_NET_CIDR} | sed "s@0.0/16@255.250@")
           METALLB_IP_RANGE="${METALLB_IP_START}-${METALLB_IP_END}"
@@ -208,7 +209,8 @@ jobs:
           psp:
             create: false
           EOF
-          
+          cat metallb_values.yaml
+
           helm install --namespace metallb-system \
             --create-namespace \
             --repo https://metallb.github.io/metallb metallb metallb \