move ThreadImport ABC error to use AbortNode

'StartShutdown' should only be used for user requested
shutdowns. Internal errors that cause a shutdown should
use 'AbortNode'.

Author: furszy

src/node/blockstorage.cpp

@@ -928,8 +928,7 @@ void ThreadImport(ChainstateManager& chainman, std::vector<fs::path> vImportFile
         for (Chainstate* chainstate : WITH_LOCK(::cs_main, return chainman.GetAll())) {
             BlockValidationState state;
             if (!chainstate->ActivateBestChain(state, nullptr)) {
-                LogPrintf("Failed to connect best block (%s)\n", state.ToString());
-                StartShutdown();
+                AbortNode(strprintf("Failed to connect best block (%s)", state.ToString()));
                 return;
             }
         }