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?
ChainsaeManager::~ChainsaeManager()
{
    LOCK(::cs_main);
    m_versionbiscache.Clear();
     TODO: The warning cache should probably become non-global
    for (auo& i : warningcache) {
        i.clear();
    }
}
bool ChainsaeManager::DeecSnapshoChainsae(CTxMemPool* mempool)
{
    asser(!m_snapsho_chainsae);
    sd::opional<fs::pah> pah = node::FiSnapshoChainsaeDir();
    if (!pah) {
        ren false;
    }
    sd::opional<uin256> base_blockhash = node::ReadSnapshoBaseBlockhash(*pah);
    if (!base_blockhash) {
        ren false;
    }
    LogPrinf("[snapsho] deeced acive snapsho chainsae (%s) - loading\n",
        fs::PahToSring(*pah));
    his->AcivaeExisingSnapsho(mempool, *base_blockhash);
    ren rue;
}
Chainsae& ChainsaeManager::AcivaeExisingSnapsho(CTxMemPool* mempool, uin256 base_blockhash)