Cleanup some old code

[roman-khimov]

Problem

Old dead code.

Solution

Remove it and fix transaction's attributes.

[codecov]

Codecov Report

Merging #1303 into master will increase coverage by 0.16%.
The diff coverage is 9.09%.

@@            Coverage Diff             @@
##           master    #1303      +/-   ##
==========================================
+ Coverage   68.15%   68.32%   +0.16%     
==========================================
  Files         216      214       -2     
  Lines       18561    18438     -123     
==========================================
- Hits        12650    12597      -53     
+ Misses       5225     5159      -66     
+ Partials      686      682       -4     

Impacted Files	Coverage Δ
pkg/core/blockchain.go	67.69% <ø> (+0.55%)	⬆️
pkg/core/dao/dao.go	68.66% <ø> (+5.34%)	⬆️
pkg/core/header_hash_list.go	68.75% <0.00%> (+13.75%)	⬆️
pkg/core/transaction/attribute.go	0.00% <0.00%> (-37.50%)	⬇️
pkg/rpc/client/rpc.go	79.39% <ø> (+1.87%)	⬆️
pkg/core/dao/cacheddao.go	81.33% <100.00%> (+13.59%)	⬆️

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