The previous commit introduced a Hive dependency loop between the tunnel
package, the node store and the egress gateway manager:

    failed to start: cycle detected in dependency graph: [scope "pprof"]
    func(node.LocalNodeStoreParams) (*node.LocalNodeStore, error) provided by
      "github.com/cilium/cilium/pkg/node".NewLocalNodeStore
      (/go/src/github.com/cilium/cilium/pkg/node/local_node_store.go:110)
        depends on func(cmd.localNodeSynchronizerParams)
          node.LocalNodeSynchronizer provided by
          "github.com/cilium/cilium/daemon/cmd".newLocalNodeSynchronizer
          (/go/src/github.com/cilium/cilium/daemon/cmd/local_node_sync.go:97)
        depends on func(tunnel.newConfigIn) (tunnel.Config, error) provided by
          "github.com/cilium/cilium/pkg/datapath/tunnel".newConfig
          (/go/src/github.com/cilium/cilium/pkg/datapath/tunnel/tunnel.go:83)
        depends on func(egressgateway.Params)
          (struct {
            dig.Out;
            *egressgateway.Manager;
            defines.NodeOut;
            tunnel.EnablerOut
          }, error) provided by
          "github.com/cilium/cilium/pkg/egressgateway".NewEgressGatewayManager
          (/go/src/github.com/cilium/cilium/pkg/egressgateway/manager.go:165)
        depends on func(identitycachecell.identityAllocatorParams)
          identitycachecell.identityAllocatorOut provided by
          "github.com/cilium/cilium/pkg/identity/cache/cell".newIdentityAllocator
          (/go/src/github.com/cilium/cilium/pkg/identity/cache/cell/cell.go:111)
        depends on func(endpointmanager.endpointManagerParams)
          endpointmanager.endpointManagerOut provided by
          "github.com/cilium/cilium/pkg/endpointmanager".newDefaultEndpointManager
          (/go/src/github.com/cilium/cilium/pkg/endpointmanager/cell.go:228)
        depends on func(node.LocalNodeStoreParams) (*node.LocalNodeStore, error)
          provided by "github.com/cilium/cilium/pkg/node".NewLocalNodeStore
          (/go/src/github.com/cilium/cilium/pkg/node/local_node_store.go:110)

This commit works around the dependency loop.

Co-authored-by: Marco Iorio <marco.iorio@isovalent.com>
Signed-off-by: Paul Chaignon <paul.chaignon@gmail.com>

Commit 7cc1d53 ("mtu: Support tunneling over IPv6 in calculations")
adjusted the MTU calculation to take IPv6 underlays into account. But
because this commit was written before the underlay-protocol flag was
introduced, it simply assumed that we're in IPv6 underlay mode if
tunneling is enabled but IPv4 isn't.

That however doesn't work for dual-stack clusters with IPv6 underlay.
The present commit fixes it to use the underlay-protocol flag.

Fixes: 7cc1d53 ("mtu: Support tunneling over IPv6 in calculations")
Signed-off-by: Paul Chaignon <paul.chaignon@gmail.com>

This commit switches one of the existing dual-stack configuration to use
an IPv6 underlay, to test subsequent changes in dual-stack mode (where
we can run more connectivity tests).

Signed-off-by: Paul Chaignon <paul.chaignon@gmail.com>