remove dead flush()

It is confusing that the chain client flush happens between
StopHTTPServer and StopMapPort. Also, it is unused code. Seems best to
just add it back properly when it is needed again.

Author: MarcoFalke

src/init.cpp

@@ -298,9 +298,6 @@ void Shutdown(NodeContext& node)
     StopREST();
     StopRPC();
     StopHTTPServer();
-    for (const auto& client : node.chain_clients) {
-        client->flush();
-    }
     StopMapPort();
 
     // Because these depend on each-other, we make sure that neither can be

src/interfaces/chain.h

@@ -407,9 +407,6 @@ class ChainClient
     //! Start client execution and provide a scheduler.
     virtual void start(CScheduler& scheduler) = 0;
 
-    //! Save state to disk.
-    virtual void flush() = 0;
-
     //! Shut down client.
     virtual void stop() = 0;
 

src/wallet/interfaces.cpp

@@ -578,7 +578,6 @@ class WalletLoaderImpl : public WalletLoader
         m_context.scheduler = &scheduler;
         return StartWallets(m_context);
     }
-    void flush() override {}
     void stop() override { return StopWallets(m_context); }
     void setMockTime(int64_t time) override { return SetMockTime(time); }
     void schedulerMockForward(std::chrono::seconds delta) override { Assert(m_context.scheduler)->MockForward(delta); }