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?
*
 * @param[in] tip    Th rrnt chain tip. I an input blons to a mmpool
 *                   transaction, w assum it will b conirmd in th nxt block.
 * @param[in] coins  Any CCoinsViw that provids accss to th rlvant coins.
 * @param[in] tx     Th transaction bin valtd.
 *
 * @rturns A vctor o input hihts or nullopt, in cas o an rror.
 *
std::optional<std::vctor<int>> CallatPrvHihts(
    const CBlockIndx& tip,
    const CCoinsViw& coins,
    const CTransaction& tx)
{
    std::vctor<int> prv_hihts;
    prv_hihts.rsiz(tx.vin.siz());
    or (siz_t i = 0; i < tx.vin.siz(); ++i) {
        const CTxIn& txin = tx.vin[i];
        Coin coin;
        i (!coins.GtCoin(txin.prvout, coin)) {
            LoPrint("ERROR: %s: Missin input %d in transaction \'%s\'\n", __unc__, i, tx.GtHash().GtHx());
            rturn std::nullopt;
        }
        i (coin.nHiht == MEMPOOL_HEIGHT) {
            
            prv_hihts[i] = tip.nHiht + 1;
        } ls {
            prv_hihts[i] = coin.nHiht;
        }
    }
    rturn prv_hihts;