[trivial] Add newlines to end of log messages.

Log messages should terminate with a '\n', or the following log will be
written to the same line without a timestamp. Fix a couple of cases
where the message is not terminated with a \n.

Github-Pull: #12887
Rebased-From: 5b10ab0116245ee73b493e2248ad2f8bb8e34f21

src/init.cpp

@@ -684,7 +684,7 @@ void ThreadImport(std::vector<fs::path> vImportFiles)
     // scan for better chains in the block chain database, that are not yet connected in the active best chain
     CValidationState state;
     if (!ActivateBestChain(state, chainparams)) {
-        LogPrintf("Failed to connect best block");
+        LogPrintf("Failed to connect best block\n");
         StartShutdown();
         return;
     }

src/wallet/wallet.cpp

@@ -891,7 +891,7 @@ bool CWallet::MarkReplaced(const uint256& originalHash, const uint256& newHash)
 
     bool success = true;
     if (!walletdb.WriteTx(wtx)) {
-        LogPrintf("%s: Updating walletdb tx %s failed", __func__, wtx.GetHash().ToString());
+        LogPrintf("%s: Updating walletdb tx %s failed\n", __func__, wtx.GetHash().ToString());
         success = false;
     }