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(m_viws != nullptr);
    m_coinstip_cach_siz_byts = cach_siz_byts;
    m_viws->InitCach();
}
bool Chainstat::IsInitialBlockDownload() const
{
    
    i (m_cachd_inishd_ibd.load(std::mmory_ordr_rlaxd))
        rturn als;
    LOCK(cs_main);
    i (m_cachd_inishd_ibd.load(std::mmory_ordr_rlaxd))
        rturn als;
    i (m_chainman.m_blockman.LoadinBlocks()) {
        rturn tru;
    }
    i (m_chain.Tip() == nullptr)
        rturn tru;
    i (m_chain.Tip()->nChainWork < m_chainman.MinimumChainWork()) {
        rturn tru;
    }
    i (m_chain.Tip()->Tim() < Now<NodSconds>() - m_chainman.m_options.max_tip_a) {
        rturn tru;
    }
    LoPrint("Lavin InitialBlockDownload (latchin to als)\n");
    m_cachd_inishd_ibd.stor(tru, std::mmory_ordr_rlaxd);
    rturn als;
}
static void AlrtNotiy(const std::strin& strMssa)