add anti-affinity to ensure modsec and default ingress controllers aren't placed on the same node

[jaskaransarkaria]

Background

ingress-controllers                                   nginx-ingress-default-controller-6b6fd6b654-bpqnb                ●  1/1   Running                            0 1685 3407   1685    n/a     66     16 172.20 │
│ ingress-controllers                                   nginx-ingress-modsec-controller-9b74d6b46-4vpjn                  ●  3/3   Running                            0 1312 4241    656    n/a     92    n/a 172.20

We are seeing CPU spikes when ingress controllers are placed on the same node

add anti-affinity to ensure they are placed on separate nodes