GH-525 Remove unused incoming::channels::transaction

plugins/chain_interface/include/eosio/chain/plugin_interface.hpp

@@ -37,10 +37,6 @@ namespace eosio { namespace chain { namespace plugin_interface {
    }
 
    namespace incoming {
-      namespace channels {
-         using transaction           = channel_decl<struct transaction_tag, packed_transaction_ptr>;
-      }
-
       namespace methods {
          // synchronously push a block/trx to a single provider, block_state_ptr may be null
          using block_sync            = method_decl<chain_plugin_interface, bool(const signed_block_ptr&, const std::optional<block_id_type>&, const block_state_ptr&), first_provider_policy>;

plugins/producer_plugin/producer_plugin.cpp

@@ -340,8 +340,6 @@ class producer_plugin_impl : public std::enable_shared_from_this<producer_plugin
 
       chain_plugin* chain_plug = nullptr;
 
-      incoming::channels::transaction::channel_type::handle   _incoming_transaction_subscription;
-
       compat::channels::transaction_ack::channel_type&        _transaction_ack_channel;
 
       incoming::methods::block_sync::method_type::handle        _incoming_block_sync_provider;
@@ -1133,13 +1131,6 @@ void producer_plugin::plugin_initialize(const boost::program_options::variables_
       }
    }
 
-   my->_incoming_transaction_subscription = app().get_channel<incoming::channels::transaction>().subscribe(
-         [this](const packed_transaction_ptr& trx) {
-      try {
-         my->on_incoming_transaction_async(trx, false, false, false, [](const auto&){});
-      } LOG_AND_DROP();
-   });
-
    my->_incoming_block_sync_provider = app().get_method<incoming::methods::block_sync>().register_provider(
          [this](const signed_block_ptr& block, const std::optional<block_id_type>& block_id, const block_state_ptr& bsp) {
       return my->on_incoming_block(block, block_id, bsp);