wrong unrealistic etas in sync w/o downloader

```
INFO[09-28|01:45:03.642] Downloading Execution History progress=1271924/1291392 ETA=134h31m12s blk/sec=2.7
INFO[09-28|01:45:28.468] [p2p] GoodPeers eth68=1273 eth67=6950
INFO[09-28|01:45:33.642] Downloading Execution History progress=1272063/1291392 ETA=67h15m36s blk/sec=5.3
INFO[09-28|01:46:03.645] P2P app=caplin peers=64
INFO[09-28|01:46:03.645] Downloading Execution History progress=1272162/1291392 ETA=96h5m8s blk/sec=3.7
INFO[09-28|01:46:33.642] Downloading Execution History progress=1272222/1291392 ETA=168h9m0s blk/sec=2.1
INFO[09-28|01:46:58.463] [mem] memory stats alloc=5.0GB sys=6.5GB
INFO[09-28|01:46:58.466] [p2p] GoodPeers eth68=1273 eth67=6951
INFO[09-28|01:46:58.476] [txpool] stat pending=0 baseFee=0 queued=0
INFO[09-28|01:47:03.642] P2P app=caplin peers=62
INFO[09-28|01:47:03.642] Downloading Execution History progress=1272357/1291392 ETA=74h44m0s blk/sec=4.8
INFO[09-28|01:47:33.642] Downloading Execution History progress=1272399/1291392 ETA=224h12m0s blk/sec=1.6
```

eta estimated wrongly.