cc_disable_ec2_metadata only handles IPv6 address

# Bug report
The cc_disable_ec2_metadata only blocks access to the EC2 IPv4 metadata server address (169.254.169.254), it does not block access to the IPv6 address, fd00:ec2::254.

## Steps to reproduce the problem

Set the following in user-data:

```
disable_ec2_metadata: true
```

## Environment details
- Cloud-init version: any
- Operating System Distribution: any
- Cloud provider, platform or installer type: AWS

## cloud-init logs

Start by locating the cc_disable_ec2_metadata component and tracing how the disable_ec2_metadata setting currently blocks the IPv4 metadata address. Verify the existing behavior, then ensure the same setting also blocks fd00:ec2::254, with checks confirming both metadata addresses are inaccessible.

Written by the indexing model from the issue text.