validation: Send correct notification during snapshot completion

If AssumeUtxo background sync is completed in this
ActivateBestChain() call, the GetRole() function
returns "normal" instead of "background" for this chainstate.
This would make the wallet (which ignores BlockConnected
notifcation for the background chainstate) process it, change
m_last_block_processed_height, and display an incorrect
balance.

Author: mzumsande

src/validation.cpp

@@ -3526,6 +3526,10 @@ bool Chainstate::ActivateBestChain(BlockValidationState& state, std::shared_ptr<
 
                 bool fInvalidFound = false;
                 std::shared_ptr<const CBlock> nullBlockPtr;
+                // BlockConnected signals must be sent for the original role;
+                // in case snapshot validation is completed during ActivateBestChainStep, the
+                // result of GetRole() changes from BACKGROUND to NORMAL.
+               const ChainstateRole chainstate_role{this->GetRole()};
                 if (!ActivateBestChainStep(state, pindexMostWork, pblock && pblock->GetHash() == pindexMostWork->GetBlockHash() ? pblock : nullBlockPtr, fInvalidFound, connectTrace)) {
                     // A system error occurred
                     return false;
@@ -3541,7 +3545,7 @@ bool Chainstate::ActivateBestChain(BlockValidationState& state, std::shared_ptr<
                 for (const PerBlockConnectTrace& trace : connectTrace.GetBlocksConnected()) {
                     assert(trace.pblock && trace.pindex);
                     if (m_chainman.m_options.signals) {
-                        m_chainman.m_options.signals->BlockConnected(this->GetRole(), trace.pblock, trace.pindex);
+                        m_chainman.m_options.signals->BlockConnected(chainstate_role, trace.pblock, trace.pindex);
                     }
                 }