message: Optimize qsim for VQE runs of large observables
  Since qsim is fast, the time it takes for analyzing large number of observed circuits is actually longer than the time to run the simulation.
  So, just bypass that mode for now and run each circuit in the vector.
diff: @@ -133,7 +133,7 @@ void QsimAccelerator::initialize(const HeterogeneousMap &params) {
  void QsimAccelerator::execute(
  std::shared_ptr<AcceleratorBuffer> buffer,
  const std::shared_ptr<CompositeInstruction> compositeInstruction) {
  - const bool qsimSimulateSamples = m_shots > 0;
  + const bool qsimSimulateSamples = m_shots > 0 && !m_vqeMode;
  const bool areAllMeasurementsTerminal =
  shotCountFromFinalStateVec(compositeInstruction);
  @@ -219,7 +219,11 @@ void QsimAccelerator::execute(
  std::shared_ptr<AcceleratorBuffer> buffer,
  const std::vector<std::shared_ptr<CompositeInstruction>>
  compositeInstructions) {
  - if (!m_vqeMode || compositeInstructions.size() <= 1) {
  + // The time to do observed circuit analysis is not optimal for a large number
  + // of circuits so just run it one by one.
  + constexpr int MAX_NUMBER_CIRCUITS_TO_ANALYZE = 100;
  + if (!m_vqeMode || compositeInstructions.size() <= 1 ||
  + compositeInstructions.size() > MAX_NUMBER_CIRCUITS_TO_ANALYZE) {
  // Cannot run VQE mode, just run each composite independently.
  for (auto &f : compositeInstructions) {
  auto tmpBuffer =
  