fix: remove duplicate vpc execution permissions

[wzyboy]

The PR removes duplicate VPC-related permissions from Lambda function execution role as they are already included in the Amazon-managed policy.

Permissions in arn:aws:iam::aws:policy/service-role/AWSLambdaVPCAccessExecutionRole:

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": [
                "logs:CreateLogGroup",
                "logs:CreateLogStream",
                "logs:PutLogEvents",
                "ec2:CreateNetworkInterface",
                "ec2:DescribeNetworkInterfaces",
                "ec2:DeleteNetworkInterface",
                "ec2:AssignPrivateIpAddresses",
                "ec2:UnassignPrivateIpAddresses"
            ],
            "Resource": "*"
        }
    ]
}

Permissions in custom JSON file:

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": [
        "ec2:CreateNetworkInterface",
        "ec2:DescribeNetworkInterfaces",
        "ec2:DeleteNetworkInterface"
      ],
      "Resource": "*"
    }
  ]
}

As shown, the permissions in custom JSON file is a subset of the Amazon-managed policy. So it's not needed and can be safely removed.

[GuptaNavdeep1983]

@wzyboy, Thanks for submitting this PR. Can you please confirm the tests done against this PR?

[wzyboy]

@GuptaNavdeep1983 I confirm that the Lambda runs fine without the duplicate permissions in our infra.

[GuptaNavdeep1983]

Steps taken to verify the PR:

1. Executed the default example with lambda_subnet_ids and lambda_security_group_ids from the base vpc.
2. Verified that scale-up lambda is able to reach the internet and perform the scaling.