Lighthouse VC to Lodestar BN time discrepancy errors

### Describe the bug

Lighthouse VC reports time discrepancy between VC and BN. This started to happen when upgrading Lighthouse to v4.2.0.

```
May 25 14:55:59.013 ERRO Time discrepancy with beacon node endpoint: http://lodestar:9596/, local_slot: 6516878, beacon_node_slot: 6516876, msg: check the system time on this host and the beacon node
May 25 15:08:47.013 ERRO Time discrepancy with beacon node endpoint: http://lodestar:9596/, local_slot: 6516942, beacon_node_slot: 6516940, msg: check the system time on this host and the beacon node
May 25 15:32:23.011 ERRO Time discrepancy with beacon node endpoint: http://lodestar:9596/, local_slot: 6517060, beacon_node_slot: 6517058, msg: check the system time on this host and the beacon node
May 25 15:49:11.012 ERRO Time discrepancy with beacon node endpoint: http://lodestar:9596/, local_slot: 6517144, beacon_node_slot: 6517142, msg: check the system time on this host and the beacon node
May 25 16:10:11.015 ERRO Time discrepancy with beacon node endpoint: http://lodestar:9596/, local_slot: 6517249, beacon_node_slot: 6517247, msg: check the system time on this host and the beacon node
```

See https://github.com/sigp/lighthouse/issues/3421#issuecomment-1764281107 for details on why this happens.

### Expected behavior

There should not be any errors about time discrepancy.

### Steps to reproduce

1. Run Lodestar BN
2. Attach Lighthouse VC with active validators (might also happen without)
3. Observe Lighthouse VC logs

### Additional context

Also reported on discord
- https://discord.com/channels/593655374469660673/593655641445367808/1111151549851385866
- https://discord.com/channels/593655374469660673/593655641445367808/1111325957169623133

See [getSyncingStatus](https://ethereum.github.io/beacon-APIs/#/Node/getSyncingStatus) beacon API.

### Versions

Lodestar: v1.8.0 / v1.9.0-rc.0
Lighthouse: v4.2.0 (does not happen with v4.1.0)