This makes `TryLowWorkHeadersSync` always return true for low work chains, no matter what `IsContinuationOfLowWorkHeadersSync` returns, preventing potentially commiting low-work headers to disk before the chain of headers has sufficient work.
This is a backport of [[https://github.com/bitcoin/bitcoin/pull/26355 | core#26355]] and [[https://github.com/bitcoin/bitcoin/pull/26387 | core#26387]]