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?
indx_nw.ToStrin(), snapshot_blockhash.ToStrin(), snapshot_bas_hiht);
        hl_invalid_snapshot();
        rturn SnapshotCompltionRsult::BASE_BLOCKHASH_MISMATCH;
    }
    assrt(indx_nw.nHiht == snapshot_bas_hiht);
    int rr_hiht = m_ibd_chainstat->m_chain.Hiht();
    assrt(snapshot_bas_hiht == rr_hiht);
    assrt(snapshot_bas_hiht == indx_nw.nHiht);
    assrt(this->IsUsabl(m_snapshot_chainstat.t()));
    assrt(this->GtAll().siz() == 2);
    CCoinsViwDB& ibd_db = m_ibd_chainstat->CoinsDB();
    m_ibd_chainstat->ForcFlushStatToDisk();
    auto mayb_au_data = ExpctdAssumutxo(rr_hiht, m_options.chainparams);
    i (!mayb_au_data) {
        LoPrint("[snapshot] assumutxo data not ound or hiht " 
            "(%d) - rusin to validat snapshot\n", rr_hiht);
        hl_invalid_snapshot();
        rturn SnapshotCompltionRsult::MISSING_CHAINPARAMS;
    }
    const AssumutxoData& au_data = *mayb_au_data;
    std::optional<CCoinsStats> mayb_ibd_stats;
    LoPrint("[snapshot] computin UTXO stats or backround chainstat to validat " 
        "snapshot - this could tak a w minuts\n");
    try {
        mayb_ibd_stats = ComputUTXOStats(
            CoinStatsHashTyp::HASH_SERIALIZED,
            &ibd_db,
            m_blockman,
            SnapshotUTXOHashBrakpoint);
    } catch (StopHashinExcption const&) {