CDK: VPC Migration

[AshCorr]

Existing resources

dotcom-rendering/dotcom-rendering/cdk/lib/__snapshots__/dotcom-rendering.test.ts.snap

Lines 119 to 127 in 7426e99

	"VPCIpBlock": Object {
	"Default": "10.248.136.0/22",
	"Description": "CIDR block for IP addresses inside this VPC",
	"Type": "String",
	},
	"VpcId": Object {
	"Description": "The VPC in which rendering instances will run",
	"Type": "AWS::EC2::VPC::Id",
	},

We don't actual configure the VPC in Cloudformation, but we need to replace our parameters with the CDK equivalent GuVPC

[cemms1]

We need to not use the default VPC ID for the AWS account #8429

EDIT: decided not to go down this route for reasons explained on the linked issue