VMM mcast pool needs to exclude vmmDomP multicast address

[tomflynn]

The current config.py defaults use 225.1.1.1-225.1.255.255 for the 'mcast_ranges' and 225.1.2.3 for 'multicast_address'

APIC is currently not smart enough to not allocate the multicast address assigned to the VMM domain to a specific EPG if it's in the pool. We hit this problem in scale testing when creating 1000s of EPGs.

The default multicast pool should be redefined to exclude this address or the default VMM address should be changed to avoid difficult to explain issues.

[tomflynn]

The next APIC release (bzmr) will reject overlaps on input so the defaults should be changed before then to avoid failures

[pforai]

Still observing this as for multiple OpenStack VMM domains the same mcast pool is created.