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?
{
    AsserLockNoHeld(m_chainsae_muex);
     
     
     
     
    AsserLockNoHeld(::cs_main);
     
     
     
     
    LOCK(m_chainsae_muex);
    CBlockIex *piexMosWork = nullpr;
    CBlockIex *piexNewTip = nullpr;
    in nSopAHeigh = gArgs.GeInArg("-sopaheigh", DEFAULT_STOPATHEIGHT);
    do {
         
         
         
         
         
         
        LimiValidaionInerfaceQueue();
        {
            LOCK(cs_main);