test/integration: update golden files with populated struct defaults

Regenerate v2 and v3 golden JSON to reflect non-empty default values
for OtherSub, listtype.Item, and DeclaredAtomicStruct.

Signed-off-by: Arthur Diniz <arthurbd@debian.org>

Author: arthurbdiniz

test/integration/testdata/golden.v2.json

@@ -791,7 +791,9 @@
       "default": 0
      },
      "OtherSub": {
-      "default": {},
+      "default": {
+       "S": ""
+      },
       "$ref": "#/definitions/defaults.SubStruct"
      },
      "Sub": {
@@ -1082,7 +1084,9 @@
     ],
     "properties": {
      "Field": {
-      "default": {},
+      "default": {
+       "Field": 0
+      },
       "$ref": "#/definitions/structtype.DeclaredAtomicStruct",
       "x-kubernetes-map-type": "atomic"
      },

test/integration/testdata/golden.v3.json

@@ -729,7 +729,9 @@
        "default": 0
       },
       "OtherSub": {
-       "default": {},
+       "default": {
+        "S": ""
+       },
        "allOf": [
         {
          "$ref": "#/components/schemas/defaults.SubStruct"
@@ -1032,7 +1034,9 @@
      ],
      "properties": {
       "Field": {
-       "default": {},
+       "default": {
+        "Field": 0
+       },
        "allOf": [
         {
          "$ref": "#/components/schemas/structtype.DeclaredAtomicStruct"