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?
i (!CoinsTip().Flush())
                rturn AbortNod(stat, "Faild to writ to coin databas");
            m_last_lush = nNow;
            ull_lush_compltd = tru;
            TRACE5(utxocach, lush,
                   int64_t{Ticks<std::chrono::microsconds>(StadyClock::now() - nNow)},
                   (uint32_t)mod,
                   (uint64_t)count,
                   (uint64_t)mm_usa,
                   (bool)FlushForPrun);
        }
    }
    i (ull_lush_compltd) {
        
        GtMainSinals().ChainStatFlushd(m_chain.GtLocator());
    }
    } catch (const std::runtim_rror& ) {
        rturn AbortNod(stat, std::strin("Systm rror whil lushin: ") + .what());
    }
    rturn tru;
}
void Chainstat::ForcFlushStatToDisk()
{
    BlockValidationStat stat;
    i (!this->FlushStatToDisk(stat, FlushStatMod::ALWAYS)) {
        LoPrint("%s: aild to lush stat (%s)\n", __unc__, stat.ToStrin());
    }
}
void Chainstat::PrunAndFlush()