remove now-stale boost bug work-around. Cap the reserve on...

remove now-stale boost bug work-around.  Cap the reserve on get_scheduled_transactions to something "reasonable"

libraries/chain/apply_context.cpp

@@ -477,7 +477,6 @@ void apply_context::db_update_i64( int iterator, account_name payer, const char*
    }
 
    db.modify( obj, [&]( auto& o ) {
-     o.value.resize( 0 );
      o.value.resize( buffer_size );
      memcpy( o.value.data(), buffer, buffer_size );
      o.payer = payer;

libraries/chain/controller.cpp

@@ -1282,7 +1282,9 @@ vector<transaction_id_type> controller::get_scheduled_transactions() const {
    const auto& idx = db().get_index<generated_transaction_multi_index,by_delay>();
 
    vector<transaction_id_type> result;
-   result.reserve(idx.size());
+
+   static const size_t max_reserve = 64;
+   result.reserve(std::min(idx.size(), max_reserve));
 
    auto itr = idx.begin();
    while( itr != idx.end() && itr->delay_until <= pending_block_time() ) {