message: refactor: replace RecursiveMutex m_chainstate_mutex with Mutex
diff: @@ -469,10 +469,11 @@ protected:
  arith_uint256 nLastPreciousChainwork = 0;
  /**
  - * the ChainState CriticalSection
  - * A lock that must be held when modifying this ChainState - held in ActivateBestChain()
  + * The ChainState Mutex
  + * A lock that must be held when modifying this ChainState - held in ActivateBestChain() and
  + * InvalidateBlock()
  */
  - RecursiveMutex m_chainstate_mutex;
  + Mutex m_chainstate_mutex;
  /**
  * Whether this chainstate is undergoing initial block download.
  