net: disable v1 connections, reconnections on clearnet

if `-v2onlyclearnet` is turned on,
- v1 addresses from addrman aren't selected and manual connections
aren't attempted for outbound connections if it's from IPV4/IPV6
networks.
- v1 downgrade mechainm is not attempted if v2 connection wasn't
successful

Author: stratospher

src/net.cpp

@@ -455,6 +455,9 @@ CNode* CConnman::ConnectNode(CAddress addrConnect, const char *pszDest, bool fCo
     std::unique_ptr<i2p::sam::Session> i2p_transient_session;
 
     for (auto& target_addr: connect_to) {
+        if (DisableV1OnClearnet(target_addr.GetNetClass()) && !use_v2transport) {
+            continue;
+        }
         if (target_addr.IsValid()) {
             const bool use_proxy{GetProxy(target_addr.GetNetwork(), proxy)};
             bool proxyConnectionFailed = false;
@@ -1893,7 +1896,7 @@ void CConnman::DisconnectNodes()
                 // Add to reconnection list if appropriate. We don't reconnect right here, because
                 // the creation of a connection is a blocking operation (up to several seconds),
                 // and we don't want to hold up the socket handler thread for that long.
-                if (pnode->m_transport->ShouldReconnectV1()) {
+                if (pnode->m_transport->ShouldReconnectV1() && !DisableV1OnClearnet(pnode->addr.GetNetClass())) {
                     reconnections_to_add.push_back({
                         .addr_connect = pnode->addr,
                         .grant = std::move(pnode->grantOutbound),