Synapse does AAAA lookups even when IPv6 is disabled

This issue has been migrated from [#14299](https://github.com/matrix-org/synapse/issues/14299).

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### Description

I run Synapse on a host with IPv6 disabled globally by adding option `ipv6.disable=1` to the kernel command line, but Synapse still does AAAA lookups for federation destinations. This unnecessarily doubles DNS traffic and possibly increases latency by wasting time looking up addresses that can't be reached.

### Steps to reproduce

- disable IPv6 globally
- start Synapse with all listeners bound to address `0.0.0.0`
- Synapse looks up AAAA records

### Homeserver

self hosted

### Synapse Version

1.69.0

### Installation Method

pip (from PyPI)

### Platform

Linux 5.15.53-1-lts, Python 3.10.5

### Relevant log output

I don't see any Synapse logs related to DNS lookups even with debug logging enabled

### Anything else that would be useful to know?

_No response_