OpenAPI: Fix ValidationError message attribute (#90846)

It's `message`, not `msg`. It's been fixed for a while here: 9ef6983612/scripts/pull-schema.sh (L46-L49)

I've also reflected the change in the tests

pkg/services/ngalert/api/api_provisioning_test.go

@@ -99,8 +99,10 @@ func TestProvisioningApi(t *testing.T) {
 				response := sut.RoutePutPolicyTree(&rc, tree)
 
 				require.Equal(t, 400, response.Status())
-				expBody := `{"message":"invalid object specification: invalid policy tree"}`
-				require.Equal(t, expBody, string(response.Body()))
+				expBody := definitions.ValidationError{Message: "invalid object specification: invalid policy tree"}
+				expBodyJSON, marshalErr := json.Marshal(expBody)
+				require.NoError(t, marshalErr)
+				require.Equal(t, string(expBodyJSON), string(response.Body()))
 			})
 		})
 

pkg/services/ngalert/api/tooling/api.json

@@ -4380,7 +4380,7 @@
   },
   "ValidationError": {
    "properties": {
-    "msg": {
+    "message": {
      "example": "error message",
      "type": "string"
     }

pkg/services/ngalert/api/tooling/definitions/shared.go

@@ -11,7 +11,7 @@ type Ack struct{}
 // swagger:model
 type ValidationError struct {
 	// example: error message
-	Msg string `json:"msg"`
+	Message string `json:"message"`
 }
 
 // swagger:model

pkg/services/ngalert/api/tooling/post.json

@@ -4379,7 +4379,7 @@
   },
   "ValidationError": {
    "properties": {
-    "msg": {
+    "message": {
      "example": "error message",
      "type": "string"
     }

pkg/services/ngalert/api/tooling/spec.json

@@ -8013,7 +8013,7 @@
     "ValidationError": {
       "type": "object",
       "properties": {
-        "msg": {
+        "message": {
           "type": "string",
           "example": "error message"
         }

public/api-merged.json

@@ -21969,7 +21969,7 @@
     "ValidationError": {
       "type": "object",
       "properties": {
-        "msg": {
+        "message": {
           "type": "string",
           "example": "error message"
         }

public/openapi3.json

@@ -12027,7 +12027,7 @@
       },
       "ValidationError": {
         "properties": {
-          "msg": {
+          "message": {
             "example": "error message",
             "type": "string"
           }