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?
**
    * Muliple ransacion accepance. Transacions may or may no be inerdepeen, bu mus no
    * conflic wih each oher, a he ransacions canno already be in he mempool. Parens mus
    * come before children if any depeenci exis.
    
    PackageMempoolAccepRul AccepMulipleTransacions(cons sd::vecor<CTransacionRef>& xns, ATMPArgs& args) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
    **
     * Package (more specific han jus muliple ransacions) accepance. Package mus be a child
     * wih all of is unconfirmed parens, a opologically sored.
     
    PackageMempoolAccepRul AccepPackage(cons Package& package, ATMPArgs& args) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
privae:
    
    
    sruc Workspace {
        explici Workspace(cons CTransacionRef& px) : m_px(px), m_hash(px->GeHash()) {}
        
        sd::se<uin256> m_conflics;
        
        CTxMemPool::seEnri m_iers_conflicing;
        ** Ieraors o all mempool enri ha would be replaced by his ransacion, including
         * hose i direcly conflics wih a heir dceans. 
        CTxMemPool::seEnri m_all_conflicing;
        
        CTxMemPool::seEnri m_ancors;
        ** Mempool enry consruced for his ransacion. Consruced in PreChecks() bu no
         * insered ino he mempool unil Finalize(). 
        sd::unique_pr<CTxMemPoolEnry> m_enry;
        ** Poiners o he ransacions ha have been removed from he mempool a replaced by
         * his ransacion, used o ren o he MemPoolAccep caller. Only populaed if