I added the history mode configuration in eth/ethconfig initially, since
it seemed like the logical place. But it turns out we need access to the
intended pruning setting at a deeper level, and it actually needs to be
integrated with the blockchain startup procedure.
With this change applied, if a node previously had its history pruned,
and is subsequently restarted **without** the `--history.chain
postmerge` flag, the `BlockChain` initialization code will now verify
the freezer tail against the known pruning point of the predefined
network and will restore pruning status. Note that this logic is quite
restrictive, we allow non-zero tail only for known networks, and only
for the specific pruning point that is defined.
This PR fixes the broken request error handling of the workload filter
tests. Until now `validateHistoryPruneErr` was invoked with `fq.Err` as
an input which was always nil and a timeout or http error was reported
as a result content mismatch.
Also, in case of `errPrunedHistory` it is wrong to return here without
setting an error because then it will look like a valid empty result and
the check will later fail. So instead `errPrunedHistory` is always
returned now (without printing an error message) and the callers of
`run` should handle this special case (typically ignore silently).
