Remove p2pEnabled from Chain interface

RPC server starts in warmup mode, it can't
process yet calls, then follows connection manager
initialization and finally RPC server get out of
warmup mode. RPC calls shouldn't be able to get
P2P disabled errors because once we initialize
g_connman it's not unset until shutdown, after
RPC server has been stopped.

src/interfaces/chain.cpp

@@ -332,7 +332,6 @@ public:
         LOCK(cs_main);
         return ::fHavePruned;
     }
-    bool p2pEnabled() override { return g_connman != nullptr; }
     bool isReadyToBroadcast() override { return !::fImporting && !::fReindex && !isInitialBlockDownload(); }
     bool isInitialBlockDownload() override { return ::ChainstateActive().IsInitialBlockDownload(); }
     bool shutdownRequested() override { return ShutdownRequested(); }