chore: bump RDS Postgres Engine Version to 16.2 (#30219)

### Issue # (if applicable)

Closes #30131 

### Reason for this change

Postgres version 15.2 is deprecated.

### Description of changes

Any and all references to Postgres 15.2 now reference 16.2 instead.

### Description of how you validated changes

Ran all changed integ and unit tests.

### Checklist
- [x] My code adheres to the [CONTRIBUTING GUIDE](https://github.com/aws/aws-cdk/blob/main/CONTRIBUTING.md) and [DESIGN GUIDELINES](https://github.com/aws/aws-cdk/blob/main/docs/DESIGN_GUIDELINES.md)

----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

Author: Leo10Gama

packages/@aws-cdk-testing/framework-integ/test/aws-rds/test/integ.instance-dual.js.snapshot/aws-cdk-rds-instance-dual-integ.assets.json

@@ -18,9 +18,6 @@
   "VPCPublicSubnet1SubnetB4246D30": {
    "Type": "AWS::EC2::Subnet",
    "Properties": {
-    "VpcId": {
-     "Ref": "VPCB9E5F0B4"
-    },
     "AvailabilityZone": {
      "Fn::Select": [
       0,
@@ -44,21 +41,24 @@
       "Key": "Name",
       "Value": "aws-cdk-rds-instance-dual-integ/VPC/PublicSubnet1"
      }
-    ]
+    ],
+    "VpcId": {
+     "Ref": "VPCB9E5F0B4"
+    }
    }
   },
   "VPCPublicSubnet1RouteTableFEE4B781": {
    "Type": "AWS::EC2::RouteTable",
    "Properties": {
-    "VpcId": {
-     "Ref": "VPCB9E5F0B4"
-    },
     "Tags": [
      {
       "Key": "Name",
       "Value": "aws-cdk-rds-instance-dual-integ/VPC/PublicSubnet1"
      }
-    ]
+    ],
+    "VpcId": {
+     "Ref": "VPCB9E5F0B4"
+    }
    }
   },
   "VPCPublicSubnet1RouteTableAssociation0B0896DC": {
@@ -75,12 +75,12 @@
   "VPCPublicSubnet1DefaultRoute91CEF279": {
    "Type": "AWS::EC2::Route",
    "Properties": {
-    "RouteTableId": {
-     "Ref": "VPCPublicSubnet1RouteTableFEE4B781"
-    },
     "DestinationCidrBlock": "0.0.0.0/0",
     "GatewayId": {
      "Ref": "VPCIGWB7E252D3"
+    },
+    "RouteTableId": {
+     "Ref": "VPCPublicSubnet1RouteTableFEE4B781"
     }
    },
    "DependsOn": [
@@ -90,9 +90,6 @@
   "VPCPublicSubnet2Subnet74179F39": {
    "Type": "AWS::EC2::Subnet",
    "Properties": {
-    "VpcId": {
-     "Ref": "VPCB9E5F0B4"
-    },
     "AvailabilityZone": {
      "Fn::Select": [
       1,
@@ -116,21 +113,24 @@
       "Key": "Name",
       "Value": "aws-cdk-rds-instance-dual-integ/VPC/PublicSubnet2"
      }
-    ]
+    ],
+    "VpcId": {
+     "Ref": "VPCB9E5F0B4"
+    }
    }
   },
   "VPCPublicSubnet2RouteTable6F1A15F1": {
    "Type": "AWS::EC2::RouteTable",
    "Properties": {
-    "VpcId": {
-     "Ref": "VPCB9E5F0B4"
-    },
     "Tags": [
      {
       "Key": "Name",
       "Value": "aws-cdk-rds-instance-dual-integ/VPC/PublicSubnet2"
      }
-    ]
+    ],
+    "VpcId": {
+     "Ref": "VPCB9E5F0B4"
+    }
    }
   },
   "VPCPublicSubnet2RouteTableAssociation5A808732": {
@@ -147,12 +147,12 @@
   "VPCPublicSubnet2DefaultRouteB7481BBA": {
    "Type": "AWS::EC2::Route",
    "Properties": {
-    "RouteTableId": {
-     "Ref": "VPCPublicSubnet2RouteTable6F1A15F1"
-    },
     "DestinationCidrBlock": "0.0.0.0/0",
     "GatewayId": {
      "Ref": "VPCIGWB7E252D3"
+    },
+    "RouteTableId": {
+     "Ref": "VPCPublicSubnet2RouteTable6F1A15F1"
     }
    },
    "DependsOn": [
@@ -162,9 +162,6 @@
   "VPCIsolatedSubnet1SubnetEBD00FC6": {
    "Type": "AWS::EC2::Subnet",
    "Properties": {
-    "VpcId": {
-     "Ref": "VPCB9E5F0B4"
-    },
     "AvailabilityZone": {
      "Fn::Select": [
       0,
@@ -210,7 +207,10 @@
       "Key": "Name",
       "Value": "aws-cdk-rds-instance-dual-integ/VPC/IsolatedSubnet1"
      }
-    ]
+    ],
+    "VpcId": {
+     "Ref": "VPCB9E5F0B4"
+    }
    },
    "DependsOn": [
     "Ipv6CidrBlock"
@@ -219,15 +219,15 @@
   "VPCIsolatedSubnet1RouteTableEB156210": {
    "Type": "AWS::EC2::RouteTable",
    "Properties": {
-    "VpcId": {
-     "Ref": "VPCB9E5F0B4"
-    },
     "Tags": [
      {
       "Key": "Name",
       "Value": "aws-cdk-rds-instance-dual-integ/VPC/IsolatedSubnet1"
      }
-    ]
+    ],
+    "VpcId": {
+     "Ref": "VPCB9E5F0B4"
+    }
    }
   },
   "VPCIsolatedSubnet1RouteTableAssociationA2D18F7C": {
@@ -244,9 +244,6 @@
   "VPCIsolatedSubnet2Subnet4B1C8CAA": {
    "Type": "AWS::EC2::Subnet",
    "Properties": {
-    "VpcId": {
-     "Ref": "VPCB9E5F0B4"
-    },
     "AvailabilityZone": {
      "Fn::Select": [
       1,
@@ -292,7 +289,10 @@
       "Key": "Name",
       "Value": "aws-cdk-rds-instance-dual-integ/VPC/IsolatedSubnet2"
      }
-    ]
+    ],
+    "VpcId": {
+     "Ref": "VPCB9E5F0B4"
+    }
    },
    "DependsOn": [
     "Ipv6CidrBlock"
@@ -301,15 +301,15 @@
   "VPCIsolatedSubnet2RouteTable9B4F78DC": {
    "Type": "AWS::EC2::RouteTable",
    "Properties": {
-    "VpcId": {
-     "Ref": "VPCB9E5F0B4"
-    },
     "Tags": [
      {
       "Key": "Name",
       "Value": "aws-cdk-rds-instance-dual-integ/VPC/IsolatedSubnet2"
      }
-    ]
+    ],
+    "VpcId": {
+     "Ref": "VPCB9E5F0B4"
+    }
    }
   },
   "VPCIsolatedSubnet2RouteTableAssociation7BF8E0EB": {
@@ -337,21 +337,21 @@
   "VPCVPCGW99B986DC": {
    "Type": "AWS::EC2::VPCGatewayAttachment",
    "Properties": {
-    "VpcId": {
-     "Ref": "VPCB9E5F0B4"
-    },
     "InternetGatewayId": {
      "Ref": "VPCIGWB7E252D3"
+    },
+    "VpcId": {
+     "Ref": "VPCB9E5F0B4"
     }
    }
   },
   "Ipv6CidrBlock": {
    "Type": "AWS::EC2::VPCCidrBlock",
    "Properties": {
+    "AmazonProvidedIpv6CidrBlock": true,
     "VpcId": {
      "Ref": "VPCB9E5F0B4"
-    },
-    "AmazonProvidedIpv6CidrBlock": true
+    }
    }
   },
   "DualstackInstanceSubnetGroupB16A837F": {
@@ -394,9 +394,9 @@
      "Ref": "DualstackInstanceSubnetGroupB16A837F"
     },
     "Engine": "postgres",
-    "EngineVersion": "15.2",
-    "MasterUsername": "postgres",
+    "EngineVersion": "16.2",
     "MasterUserPassword": "7959866cacc02c2d243ecfe177464fe6",
+    "MasterUsername": "postgres",
     "MultiAZ": false,
     "NetworkType": "DUAL",
     "PubliclyAccessible": false,
@@ -453,9 +453,9 @@
      "Ref": "Ipv4InstanceSubnetGroup6E04EDDC"
     },
     "Engine": "postgres",
-    "EngineVersion": "15.2",
-    "MasterUsername": "postgres",
+    "EngineVersion": "16.2",
     "MasterUserPassword": "7959866cacc02c2d243ecfe177464fe6",
+    "MasterUsername": "postgres",
     "MultiAZ": false,
     "NetworkType": "IPV4",
     "PubliclyAccessible": false,