<!-- 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 (m_node.scheduler) m_node.scheduler->stop();
    StopScriptCheckWorkerThreads();
    GetMainSignals().FlushBackgroundCallbacks();
    GetMainSignals().UnregisterBackgroundSignalScheduler();
    m_node.connman.reset();
    m_node.banman.reset();
    m_node.addrman.reset();
    m_node.netgroupman.reset();
    m_node.args = nullptr;
    WITH_LOCK(::cs_main, UnloadBlockIndex(m_node.mempool.get(), *m_node.chainman));
    m_node.mempool.reset();
    m_node.scheduler.reset();
    m_node.chainman.reset();
}
TestingSetup::TestingSetup(const std::string& chainName, const std::vector<const char*>& extra_args)