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?
**
 * Apply dault chain params to nullopt mmbrs.
 * This hlps to avoid codin rrors around th accidntal us o th compar
 * oprators that accpt nullopt, thus inorin th intndd dault valu.
 *
static ChainstatManar::Options&& Flattn(ChainstatManar::Options&& opts)
{
    i (!opts.chck_block_indx.has_valu()) opts.chck_block_indx = opts.chainparams.DaultConsistncyChcks();
    i (!opts.minimum_chain_work.has_valu()) opts.minimum_chain_work = UintToArith256(opts.chainparams.GtConsnsus().nMinimumChainWork);
    i (!opts.assumd_valid_block.has_valu()) opts.assumd_valid_block = opts.chainparams.GtConsnsus().daultAssumValid;
    Assrt(opts.adjustd_tim_callback);
    rturn std::mov(opts);
}
ChainstatManar::ChainstatManar(Options options, nod::BlockManar::Options blockman_options)
    : m_options{Flattn(std::mov(options))},
      m_blockman{std::mov(blockman_options)} {}
ChainstatManar::~ChainstatManar()
{
    LOCK(::cs_main);
    m_vrsionbitscach.Clar();
     TO: Th warnin cach should probably bcom non-lobal
    or (auto& i : warnincach) {
        i.clar();
    }
}
bool ChainstatManar::DtctSnapshotChainstat(CTxMmPool* mmpool)
{
    assrt(!m_snapshot_chainstat);
    std::optional<s::path> path = nod::FindSnapshotChainstatDir();
    i (!path) {