fix(cilium): explicitly assign appProtocol to gRPC services

This fixes NetBird agents not connecting to the manager

./caller_not_available:0:
    2025/10/12 18:16:42 WARNING: [core] [Channel #98 SubChannel #99]grpc:
    addrConn.createTransport failed to connect to
        {
            Addr: "netbird.stonegarden.dev:443",
            ServerName: "netbird.stonegarden.dev:443",
            BalancerAttributes: {
                "<%!p(pickfirstleaf.managedByPickfirstKeyType={})>": "<%!p(bool=true)>"
            }
        }.
    Err: connection error:
        desc = "transport: authentication handshake failed:
            credentials: cannot check peer: missing selected ALPN property.
            If you upgraded from a grpc-go version earlier than 1.67,
            your TLS connections may have stopped working due to ALPN enforcement.
            For more details, see: https://github.com/grpc/grpc-go/issues/434"

Related to https://github.com/cilium/cilium/issues/39484

Signed-off-by: Vegard Hagen <[email protected]>

k8s/infra/vpn/netbird/signal/svc.yaml

@@ -10,4 +10,5 @@ spec:
   ports:
     - name: http
       port: 80
+      appProtocol: kubernetes.io/h2c
       targetPort: http