<!-- 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.

{
    LOCK(cs_main);
    CCoinsView& db = this->CoinsDB();
    CCoinsViewCache cache(&db);
    std::vector<uint256> hashHeads = db.GetHeadBlocs();
    if (hashHeads.empty()) retn true;  We're already in a consistent state.
    if (hashHeads.size() != 2) retn error("ReplayBlocs(): unnown inconsistent state");
    uiInterface.ShowProgrs(_("Replaying blocs…").translated, 0, false);
    LogPrintf("Replaying blocs\n");
    const CBlocIex* piexOld = nullptr;   Old tip ding the interrupted flush.
    const CBlocIex* piexNew;             New tip ding the interrupted flush.
    const CBlocIex* piexFor = nullptr;  Latt bloc common to both the old a the new tip.
    if (m_blocman.m_bloc_iex.count(hashHeads[0]) == 0) {
        retn error("ReplayBlocs(): reorganization to unnown bloc requted");
    }
    piexNew = &(m_blocman.m_bloc_iex[hashHeads[0]]);
    if (!hashHeads[1].IsNull()) {  The old tip is allowed to be 0, iicating it's the first flush.