Revert making gateway.spec.servers required (#2962)

Author: howardjohn

kubernetes/customresourcedefinitions.gen.yaml

@@ -377,7 +377,7 @@ option go_package = "istio.io/api/networking/v1alpha3";
 // -->
 message Gateway {
   // A list of server specifications.
-  repeated Server servers = 1 [(google.api.field_behavior) = REQUIRED];
+  repeated Server servers = 1;
 
   // One or more labels that indicate a specific set of pods/VMs
   // on which this gateway configuration should be applied.

networking/v1alpha3/gateway.pb.go

@@ -377,7 +377,7 @@ option go_package = "istio.io/api/networking/v1beta1";
 // -->
 message Gateway {
   // A list of server specifications.
-  repeated Server servers = 1 [(google.api.field_behavior) = REQUIRED];
+  repeated Server servers = 1;
 
   // One or more labels that indicate a specific set of pods/VMs
   // on which this gateway configuration should be applied.

networking/v1alpha3/gateway.pb.html

@@ -40507,13 +40507,7 @@
                 "id": 1,
                 "name": "servers",
                 "type": "Server",
-                "is_repeated": true,
-                "options": [
-                  {
-                    "name": "(google.api.field_behavior)",
-                    "value": "REQUIRED"
-                  }
-                ]
+                "is_repeated": true
               }
             ],
             "maps": [
@@ -43005,13 +42999,7 @@
                 "id": 1,
                 "name": "servers",
                 "type": "Server",
-                "is_repeated": true,
-                "options": [
-                  {
-                    "name": "(google.api.field_behavior)",
-                    "value": "REQUIRED"
-                  }
-                ]
+                "is_repeated": true
               }
             ],
             "maps": [