wallet: Reset RPC Pay ID on node switch

RPC pay client ID is sent with each RPC request, set a new secret every time we switch nodes to mitigate trivial correlation

src/wallet/wallet2.cpp

@@ -1319,6 +1319,9 @@ bool wallet2::set_daemon(std::string daemon_address, boost::optional<epee::net_u
   m_trusted_daemon = trusted_daemon;
   if (changed)
   {
+    if (!m_persistent_rpc_client_id) {
+      set_rpc_client_secret_key(rct::rct2sk(rct::skGen()));
+    }
     m_rpc_payment_state.expected_spent = 0;
     m_rpc_payment_state.discrepancy = 0;
     m_node_rpc_proxy.invalidate();