[AWS::Lambda::Function] - [BUG] - VpcConfig.Ipv6AllowedForDualStack does not reset when removed from template

### Name of the resource

AWS::Lambda::Function

### Resource Name

_No response_

### Issue Description

When Lambda is deployed into VPC with IPV6 support enabled and then updated to remove it from VPC, an error is produced.

This can be worked around by first, manually unsetting the `Ipv6AllowedForDualStack` flag in VPC configuration, either in UI console or CLI and then running the deployment with updated template.

### Expected Behavior

Lambda should deploy without error and manual intervention.

### Observed Behavior

Error message:
> Resource handler returned message: "Ipv6AllowedForDualStack cannot be true without subnet or security groups. Please remove Ipv6AllowedForDualStack value from your request and try again.

### Test Cases

Deploy VPC with IPV6 subnets and a Lambda function using that vpc, `VpcConfig` with `Ipv6AllowedForDualStack` set to `true` (you will have to set subnet and security group as well).
Change the template to disassociate Lambda from the VPC and remove the `VpcConfig` section.

Lambda should redeploy without errors.

### Other Details

_No response_

Start with the deployment sequence in the Test Cases: create the VPC-backed Lambda with VpcConfig.Ipv6AllowedForDualStack set to true, then remove VpcConfig and redeploy. Done means the update succeeds without manual console or CLI cleanup and without the reported error.

Written by the indexing model from the issue text.