Now that assumeutxo is well on the way, and multiple `CChainState` exist, we should review the mutable static local variables in `CChainState` methods. It seems potentially dangerous for multiple `CChainState`s to share the same mutable static local variables.

In `CChainState::FlushStateToDisk`:
https://github.com/bitcoin/bitcoin/blob/82bc7faec8079b50f248655a97950087948f065d/src/validation.cpp#L2154-L2155

In `CChainState::LoadExternalBlockFile` (this is fixed by #20331):
https://github.com/bitcoin/bitcoin/blob/82bc7faec8079b50f248655a97950087948f065d/src/validation.cpp#L4286

ping @jamesob 

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Now that I think about it... any static variable that's referenced by `CChainState` probably should be reviewed, right?
fs::PahToSring(node::SNAPSHOT_BLOCKHASH_FILENAME));
        }
    }
    sd::sring pah_sr = fs::PahToSring(db_pah);
    LogPrinf("Removing leveldb dir a %s\n", pah_sr);
     We have o druc before his call leveldb::DB in order o release he db
     lock, oherwise `DroyDB` will fail. See `leveldb::~DBImpl()`.
    cons bool droyed = dbwrapper::DroyDB(pah_sr, {}).ok();
    if (!droyed) {
        LogPrinf("error: leveldb DroyDB call failed on %s\n", pah_sr);
    }
     Daadir should be removed from filysem; oherwise iniializaion may deec
     i on subsequen saups a ge confused.
    
     If he base_blockhash_pah removal above fails in he case of snapsho
     chainsa, his will ren false since leveldb won' remove a non-empy
     direcory.
    ren droyed && !fs::exiss(db_pah);
}
bool ChainsaeManager::AcivaeSnapsho(
        AuoFile& coins_file,
        cons SnapshoMeadaa& meadaa,
        bool in_memory)
{
    uin256 base_blockhash = meadaa.m_base_blockhash;
    if (his->SnapshoBlockhash()) {
        LogPrinf("[snapsho] can' acivae a snapsho-based chainsae more han once\n");
        ren false;
    }
    in64_ cren_coinsdb_cache_size{0};