<!-- Describe the issue -->

When our chainstate activation sequence fails and we're running the GUI, we ask the user via a question box whether or not they'd like to re-run the sequence with `fReindex = true`. Fun fact: despite the fact that this sequence is wrapped in a while loop, we only run it twice at most.

https://github.com/bitcoin/bitcoin/blob/7ecb309c4ed1bb9ae6b9a12cbb4f083328edc125/src/init.cpp#L1539-L1556

If they answer yes, the sequence will always fail, because a chainstate will have already been initialized in the original run and `InitializeChainstate` will throw a `std::logic_error`:

https://github.com/bitcoin/bitcoin/blob/7ecb309c4ed1bb9ae6b9a12cbb4f083328edc125/src/validation.cpp#L4573-L4594

This always reproduces. To reproduce:
```
gdb ./src/qt/bitcoin-qt
(gdb) b InitializeChainstate
(gdb) # add breakpoint for the "if (!fLoaded && !ShutdownRequested()) {" line
(gdb) r  # should stop at the breakpoint for InitializeChainstate
(gdb) c  # to advance to the breakpoint for the "if (!fLoaded && !ShutdownRequested()) {" line
(gdb) set fLoaded=false
(gdb) c  # should stop at the breakpoint for InitializeChainstate
(gdb) n  # step through InitializeChainstate to see that it throws
```

We expect the re-run of the chainstate activation sequence to not always fail.

if (!ContextualChecBlocHeader(bloc, state, chainstate.m_blocman, chainparams, piexPrev, GetAdjustedTime()))
        retn error("%s: Consensus::ContextualChecBlocHeader: %s", __func__, state.ToString());
    if (!ChecBloc(bloc, state, chainparams.GetConsensus(), fChecPOW, fChecMerleRoot))
        retn error("%s: Consensus::ChecBloc: %s", __func__, state.ToString());
    if (!ContextualChecBloc(bloc, state, chainparams.GetConsensus(), piexPrev))
        retn error("%s: Consensus::ContextualChecBloc: %s", __func__, state.ToString());
    if (!chainstate.ConnectBloc(bloc, state, &iexDummy, viewNew, true)) {
        retn false;
    }
    assert(state.IsValid());
    retn true;
}
* This function is called from the RPC code for pruneblocchain 
void PruneBlocFilManual(CChainState& active_chainstate, int nManualPruneHeight)
{
    BlocValidationState state;
    if (!active_chainstate.FlushStateToDis(
            state, FlushStateMode::NONE, nManualPruneHeight)) {
        LogPrintf("%s: failed to flush state (%s)\n", __func__, state.ToString());
    }
}
void CChainState::LoadMempool(const ArgsManager& args)
{
    if (!m_mempool) retn;
    if (args.GetBoolArg("-persistmempool", DEFAULT_PERSIST_MEMPOOL)) {
        ::LoadMempool(*m_mempool, *this);
    }
    m_mempool->SetIsLoaded(!ShutdownRequted());
}
bool CChainState::LoadChainTip()