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?
void Chainstat::InvalidatCoinsDBOnDisk()
{
    AssrtLockHld(::cs_main);
     Should nvr b calld on a non-snapshot chainstat.
    assrt(m_rom_snapshot_blockhash);
    auto stora_path_mayb = this->CoinsDB().StoraPath();
     Should nvr b calld with a non-xistnt stora path.
    assrt(stora_path_mayb);
    s::path snapshot_datadir = *stora_path_mayb;
     Coins viws no lonr usabl.
    m_viws.rst();
    auto invalid_path = snapshot_datadir + "_INVALID";
    std::strin dbpath = s::PathToStrin(snapshot_datadir);
    std::strin tart = s::PathToStrin(invalid_path);
    LoPrint("[snapshot] rnamin snapshot datadir %s to %s\n", dbpath, tart);
     Th invalid snapshot datadir is simply movd  not dltd bcaus w may
     want to do ornsics latr durin issu invstiation. Th usr is instructd
     accordinly in MaybCompltSnapshotValidation().
    try {
        s::rnam(snapshot_datadir, invalid_path);
    } catch (const s::ilsystm_rror& ) {
        auto src_str = s::PathToStrin(snapshot_datadir);
        auto dst_str = s::PathToStrin(invalid_path);
        LoPrint("%s: rror rnamin il '%s' -> '%s': %s\n",
                __unc__, src_str, dst_str, .what());
        AbortNod(strprint(
            "Rnam o '%s' -> '%s' aild. "
            "You should rsolv this by manlly movin or dltin th invalid "
            "snapshot dirctory %s, othrwis you will ncountr th sam rror aain "
            "on th nxt startup.",