post-fulu: network thread bottle neck

### Describe the bug

the gossip validation job time was computed against gossipsub seenTimestampSec and it's always <=250ms

but elapsed time till received, where we compute against the start slot is terrible

it means gossipsub send DataColumnSidecars very late into the slot, it's confirmed through network thread event loop too

### Expected behavior

network thread should receive/send DataColumnSidecars sooner

### Steps to reproduce

_No response_

### Additional context

_No response_

### Operating system

Linux

### Lodestar version or commit hash

v1.36.0