<!-- 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.

{
    const MapCheckpoints& checkpoints = data.mapCheckpoints;
    for (const MapCheckpoints::value_type& i : reverse_iterate(checkpoints)) {
        const uint256& hash = i.second;
        const CBlockIndex* pindex = LookupBlockIndex(hash);
        if (pindex) {
            return pindex;
        }
    }
    return nullptr;
}
bool BlockManager::IsBlockPruned(const CBlockIndex* pblockindex)
{
    AssertLockHeld(::cs_main);
    return (m_have_pruned && !(pblockindex->nStatus & BLOCK_HAVE_DATA) && pblockindex->nTx > 0);
}
const CBlockIndex* GetFirstStoredBlock(const CBlockIndex* start_block) {
    AssertLockHeld(::cs_main);
    assert(start_block);
    const CBlockIndex* last_block = start_block;
    while (last_block->pprev && (last_block->pprev->nStatus & BLOCK_HAVE_DATA)) {
        last_block = last_block->pprev;
    }
    return last_block;
}
void CleanupBlockRevFiles()
{
    std::map<std::string, fs::path> mapBlockFiles;