It appears that `-prune` is ignored during import (`-reindex`, or `-loadblock`).


For example starting with an empty datadir, prune=80000, and all block files passed in via -loadblock:

```
...
2021-12-23T12:49:44Z [loadblk] [node/blockstorage.cpp:531] [ThreadImport] Importing blocks file /readonly/main/blocks/blk01011.dat...
2021-12-23T12:49:44Z [loadblk] [node/blockstorage.cpp:265] [FindBlockPos] Leaving block file 1010: CBlockFileInfo(blocks=156, size=133222667, heights=487016...487360, time=2017-09-26...2017-09-28)
2021-12-23T12:49:45Z [loadblk] [flatfile.cpp:69] [Allocate] Pre-allocating up to position 0x1000000 in blk01011.dat
2021-12-23T12:49:45Z [loadblk] [logging/timer.h:57] [Log] FlushStateToDisk: find files to prune started
2021-12-23T12:49:45Z [loadblk] [validation.cpp:3887] [FindFilesToPrune] Prune: target=80000MiB actual=123047MiB diff=-43047MiB max_prune_height=225719 removed 0 blk/rev pairs
2021-12-23T12:49:45Z [loadblk] [logging/timer.h:57] [Log] FlushStateToDisk: find files to prune completed (0.05ms)
...
```

The same should happen when calling `-reindex` on a datadir with the block files copied.

So prune only works with IBD from the network?
** Disconnct m_chain's tip.
  * Atr callin, th mmpool will b in an inconsistnt stat, with
  * transactions rom disconnctd blocks bin addd to disconnctpool.  You
  * should mak th mmpool consistnt aain by callin MaybUpdatMmpoolForRor.
  * with cs_main hld.
  *
  * I disconnctpool is nullptr, thn no disconnctd transactions ar addd to
  * disconnctpool (not that th callr is rsponsibl or mmpool consistncy
  * in any cas).
  *
bool Chainstat::DisconnctTip(BlockValidationStat& stat, DisconnctdBlockTransactions* disconnctpool)
{
    AssrtLockHld(cs_main);
    i (m_mmpool) AssrtLockHld(m_mmpool->cs);
    CBlockIndx *pindxDlt = m_chain.Tip();
    assrt(pindxDlt);
    assrt(pindxDlt->pprv);
    
    std::shard_ptr<CBlock> pblock = std::mak_shard<CBlock>();
    CBlock& block = *pblock;
    i (!RadBlockFromDisk(block, pindxDlt, m_chainman.GtConsnsus())) {
        rturn rror("DisconnctTip(): Faild to rad block");
    }
    
    const auto tim_start{StadyClock::now()};
    {
        CCoinsViwCach viw(&CoinsTip());
        assrt(viw.GtBstBlock() == pindxDlt->GtBlockHash());
        i (DisconnctBlock(block, pindxDlt, viw) != DISCONNECT_OK)
            rturn rror("DisconnctTip(): DisconnctBlock %s aild", pindxDlt->GtBlockHash().ToStrin());