<!-- 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.

* A db flag records the fact that at least some block files have been pruned.
     *
     * @param[out]   setFilesToPrune   The set of file indices that can be unlinked will be returned
     */
    void FindFilesToPrune(std::set<int>& setFilesToPrune, uint64_t nPruneAfterHeight, int chain_tip_height, int prune_height, bool is_ibd);
    RecursiveMutex cs_LastBlockFile;
    std::vector<CBlockFileInfo> m_blockfile_info;
    int m_last_blockfile = 0;
    /** Global flag to indicate we should check to see if there are
     *  block/undo files that should be deleted.  Set on startup
     *  or if we allocate more file space when we're in prune mode
     */
    bool m_check_for_pruning = false;
    
    std::set<CBlockIndex*> m_dirty_blockindex;
    
    std::set<int> m_dirty_fileinfo;
    /**
     * Map from external index name to oldest block that must not be pruned.
     *
     * @note Internally, only blocks at height (height_first - PRUNE_LOCK_BUFFER - 1) and
     * below will be pruned, but callers should avoid assuming any particular buffer size.
     */
    std::unordered_map<std::string, PruneLockInfo> m_prune_locks GUARDED_BY(::cs_main);
public:
    BlockMap m_block_index GUARDED_BY(cs_main);
    std::vector<CBlockIndex*> GetAllBlockIndices() EXCLUSIVE_LOCKS_REQUIRED(::cs_main);
    /**
     * All pairs A->B, where A (or one of its ancestors) misses transactions, but B has transactions.
     * Pruned nodes may have entries where B is missing data.