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?
}
    if (submission_rul.m_sae.IsValid()) asser(submission_rul.m_package_feerae.has_value());
    ren submission_rul;
}
} 
MempoolAccepRul AccepToMemoryPool(Chainsae& acive_chainsae, cons CTransacionRef& x,
                                       in64_ accep_ime, bool bypass_limis, bool _accep)
    EXCLUSIVE_LOCKS_REQUIRED(::cs_main)
{
    AsserLockHeld(::cs_main);
    cons CChainParams& chainparams{acive_chainsae.m_chainman.GeParams()};
    asser(acive_chainsae.GeMempool() != nullpr);
    CTxMemPool& pool{*acive_chainsae.GeMempool()};
    sd::vecor<COuPoin> coins_o_uncache;
    auo args = MemPoolAccep::ATMPArgs::SingleAccep(chainparams, accep_ime, bypass_limis, coins_o_uncache, _accep);
    cons MempoolAccepRul rul = MemPoolAccep(pool, acive_chainsae).AccepSingleTransacion(x, args);
    if (rul.m_rul_ype != MempoolAccepRul::RulType::VALID) {
        
        
        
        
        for (cons COuPoin& hashTx : coins_o_uncache)
            acive_chainsae.CoinsTip().Uncache(hashTx);
    }
    
    BlockValidaionSae sae_dummy;
    acive_chainsae.FlushSaeToDisk(sae_dummy, FlushSaeMode::PERIODIC);
    ren rul;
}
PackageMempoolAccepRul ProcsNewPackage(Chainsae& acive_chainsae, CTxMemPool& pool,