Fix Cfn-lint W1028

Example failures https://github.com/aws/aws-parallelcluster/actions/runs/10185517412/job/28175271776?pr=6372

Analysis aws-cloudformation/cfn-lint#3551 (comment)

Signed-off-by: Hanwen <hanwenli@amazon.com>

Author: hanwen-cluster

cloudformation/networking/public-private.cfn.json

@@ -119,15 +119,7 @@
       "Properties": {
         "DestinationCidrBlock": "0.0.0.0/0",
         "GatewayId": {
-          "Fn::If": [
-            "CreateInternetGateway",
-            {
-              "Ref": "InternetGateway"
-            },
-            {
-              "Ref": "InternetGatewayId"
-            }
-          ]
+          "Ref": "InternetGateway"
         },
         "RouteTableId": {
           "Ref": "RouteTablePublic"
@@ -140,15 +132,7 @@
       "Properties": {
         "DestinationCidrBlock": "0.0.0.0/0",
         "GatewayId": {
-          "Fn::If": [
-            "CreateInternetGateway",
-            {
-              "Ref": "InternetGateway"
-            },
-            {
-              "Ref": "InternetGatewayId"
-            }
-          ]
+          "Ref": "InternetGatewayId"
         },
         "RouteTableId": {
           "Ref": "RouteTablePublic"

cloudformation/networking/public.cfn.json

@@ -108,15 +108,7 @@
       "Properties": {
         "DestinationCidrBlock": "0.0.0.0/0",
         "GatewayId": {
-          "Fn::If": [
-            "CreateInternetGateway",
-            {
-              "Ref": "InternetGateway"
-            },
-            {
-              "Ref": "InternetGatewayId"
-            }
-          ]
+          "Ref": "InternetGateway"
         },
         "RouteTableId": {
           "Ref": "RouteTablePublic"
@@ -129,15 +121,7 @@
       "Properties": {
         "DestinationCidrBlock": "0.0.0.0/0",
         "GatewayId": {
-          "Fn::If": [
-            "CreateInternetGateway",
-            {
-              "Ref": "InternetGateway"
-            },
-            {
-              "Ref": "InternetGatewayId"
-            }
-          ]
+          "Ref": "InternetGatewayId"
         },
         "RouteTableId": {
           "Ref": "RouteTablePublic"