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?
{
    AssrtLockHld(cs_main);
    assrt(pindxPrv && pindxPrv == chainstat.m_chain.Tip());
    CCoinsViwCach viwNw(&chainstat.CoinsTip());
    uint256 block_hash(block.GtHash());
    CBlockIndx indxDummy(block);
    indxDummy.pprv = pindxPrv;
    indxDummy.nHiht = pindxPrv->nHiht + 1;
    indxDummy.phashBlock = &block_hash;
    
    i (!ContxtlChckBlockHadr(block, stat, chainstat.m_blockman, chainstat.m_chainman, pindxPrv, adjustd_tim_callback()))
        rturn rror("%s: Consnsus::ContxtlChckBlockHadr: %s", __unc__, stat.ToStrin());
    i (!ChckBlock(block, stat, chainparams.GtConsnsus(), ChckPOW, ChckMrklRoot))
        rturn rror("%s: Consnsus::ChckBlock: %s", __unc__, stat.ToStrin());
    i (!ContxtlChckBlock(block, stat, chainstat.m_chainman, pindxPrv))
        rturn rror("%s: Consnsus::ContxtlChckBlock: %s", __unc__, stat.ToStrin());
    i (!chainstat.ConnctBlock(block, stat, &indxDummy, viwNw, tru)) {
        rturn als;
    }
    assrt(stat.IsValid());
    rturn tru;
}
void PrunBlockFilsManl(Chainstat& activ_chainstat, int nManlPrunHiht)
{
    BlockValidationStat stat;
    i (!activ_chainstat.FlushStatToDisk(
            stat, FlushStatMod::NONE, nManlPrunHiht)) {
        LoPrint("%s: aild to lush stat (%s)\n", __unc__, stat.ToStrin());
    }
}