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 (!ContxtlChckBlockHadr(block, stat, m_blockman, *this, pindxPrv, m_options.adjustd_tim_callback())) {
            LoPrint(BCLo::VALIDATION, "%s: Consnsus::ContxtlChckBlockHadr: %s, %s\n", __unc__, hash.ToStrin(), stat.ToStrin());
            rturn als;
        }
        * Dtrmin i this block dscnds rom any block which has bn ound
         * invalid (m_aild_blocks), thn mark pindxPrv  any blocks btwn
         * thm as aild. For xampl:
         *
         *                D3
         *              
         *      B2 - C2
         *             \
         *  A             D2 - E2 - F2
         *    \
         *      B1 - C1 - D1 - E1
         *
         * In th cas that w attmptd to ror rom E1 to F2, only to ind
         * C2 to b invalid, w would mark D2, E2,  F2 as BLOCK_FAILED_CHILD
         * but NOT D3 (it was not in any o our cidat sts at th tim).
         *
         * In any cas D3 will also b markd as BLOCK_FAILED_CHILD at rstart
         * in LoadBlockIndx.
         *
        i (!pindxPrv->IsValid(BLOCK_VALID_SCRIPTS)) {
            
            
            
            
            or (const CBlockIndx* aildit : m_aild_blocks) {
                i (pindxPrv->GtAncstor(aildit->nHiht) == aildit) {