Antrea Agent should fail when enabling Multicast with WireGuard

[antoninbas]

Describe the bug
It seems to me that Multicast and WireGuard cannot be used together in Antrea.
The Multicast code assumes that in encap mode, an OVS tunnel port is created:

antrea/pkg/agent/openflow/multicast.go

Line 245 in ca5dc45

MatchInPort(f.tunnelPort).

This is not the case when using WireGuard, as tunneling is then handled by Linux and not by OVS (inter-Node traffic is sent through the antrea-wg0 interface).

To Reproduce
Install the latest Antrea (from main branch) and enable both Multicast and Wireguard.

Expected
The Antrea Agent should reject this configuration.

Actual behavior
The Antrea Agent accepts the configuration and starts normally. The following flow (and potentially others) is installed, even though port 1 (reserved for the tunnel port) does not exist:

 cookie=0x2050000000000, duration=2612.449s, table=Classifier, n_packets=0, n_bytes=0, priority=210,ip,in_port=1,nw_dst=224.0.0.0/4 actions=load:0x1->NXM_NX_REG0[0..3],resubmit(,MulticastEgressRule)

Versions:
Use latest Antrea, to ensure you have this change: #5885
Even though #5885 stopped creating the tunnel interface and brought this behavior to the surface, #5885 is not responsible for this "bug". Multicast was never compatible with WireGuard to begin with.

cc @tnqn @wenyingd @ceclinux

[wenyingd]

I could add precheck for this.