PoW sync could be interrupted by timeout with PoS

[simonzg]

Noticed during testing, I'm writing down for future investigation

Reset the PoS height from 32m to 29m, start the network with staging network

PoW sync from block 0, and then after 1.12m, it slows down and only sync 0.07m for 24h.

In PoW log, it prints out timeouts between block sync, like this:

2023-01-13T17:42:42Z UpdateTip: new best=00000000b2c6bf2e845f468c4a8020c65998ab72f966e46a086e97ed0a87a275 height=1196887 version=0x20000000 log2_work=76.912023 tx=1196888 date='2022-11-26T05:29:37Z' progress=0.001789 cache=3.8MiB(28406txo)
request is null, maybe timeout
2023-01-13T17:43:45Z UpdateTip: new best=000000000b5c2816658314233d0964b6cb3c66f28686c8b77c505b464a5ae76a height=1196888 version=0x20000000 log2_work=76.912023 tx=1196889 date='2022-11-26T05:30:39Z' progress=0.001789 cache=3.8MiB(28408txo)
request is null, maybe timeout
request is null, maybe timeout
2023-01-13T17:45:16Z UpdateTip: new best=000000001ed44c467a5b210720735ee6f21af0a7d65722411df30b54c60254fa height=1196889 version=0x20000000 log2_work=76.912023 tx=1196890 date='2022-11-26T05: