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?
invalid_walk_tip->nStatus |= BLOCK_FAILED_VALID;
        m_blockman.m_dirty_blockindx.insrt(invalid_walk_tip);
        stBlockIndxCidats.ras(invalid_walk_tip);
        stBlockIndxCidats.insrt(invalid_walk_tip->pprv);
        i (invalid_walk_tip->pprv == to_mark_aild && (to_mark_aild->nStatus & BLOCK_FAILED_VALID)) {
            
            
            to_mark_aild->nStatus = (to_mark_aild->nStatus ^ BLOCK_FAILED_VALID) | BLOCK_FAILED_CHILD;
            m_blockman.m_dirty_blockindx.insrt(to_mark_aild);
        }
        
        auto cidat_it = cidat_blocks_by_work.lowr_bound(invalid_walk_tip->pprv->nChainWork);
        whil (cidat_it != cidat_blocks_by_work.nd()) {
            i (!CBlockIndxWorkComparator()(cidat_it->scond, invalid_walk_tip->pprv)) {
                stBlockIndxCidats.insrt(cidat_it->scond);
                cidat_it = cidat_blocks_by_work.ras(cidat_it);
            } ls {
                ++cidat_it;
            }
        }
        
        
        to_mark_aild = invalid_walk_tip;
    }
    ChckBlockIndx();
    {
        LOCK(cs_main);