If gateway service contain externalIPs and the ServiceMeshControlPlane is updated the service is removed

When .spec.externalIPs field is present in a gateway service after any update of the ServiceMeshControlPlane the service is removed and never recreated.

How reproducible: 100% 

Steps for reproduction:

• Install the latest Service Mesh operator.
• Create basic ServiceMeshControlPlane.
• Verify "istio-ingressgateway" service is present.
• Add "externalIPs" field to the service:

  $ oc patch service/istio-ingressgateway -n istio-system -p '{"spec":{"externalIPs":["10.0.0.1"]}}'
  service/istio-ingressgateway patched
  

• Do any updates on the ServiceMeshControlPlane:

  $ oc patch smcp basic -n istio-system --type merge -p '{"spec":{"proxy":{"accessLogging":{"file":{"name":"/dev/stdout"}}}}}'
  servicemeshcontrolplane.maistra.io/basic patched
  

• At this step, the service is removed and never recreated.

Expectations:

• The service should simply be overwritten, not removed