init: add exe name to bitcoind, bitcoin-node -version output to be able to distinguish these in tests

Github-Pull: #33229
Rebased-From: 0972f55040

src/init/bitcoin-gui.cpp

@@ -39,6 +39,7 @@ public:
     // bitcoin-node accepts the option, and bitcoin-gui accepts all bitcoin-node
     // options and will start the node with those options.
     bool canListenIpc() override { return true; }
+    const char* exeName() override { return EXE_NAME; }
     node::NodeContext m_node;
     std::unique_ptr<interfaces::Ipc> m_ipc;
 };