fix: eth: correctly encode and simplify native input/output encoding

[simlecode]

关联的Issues (Related Issues)

close #6220

改动 (Proposed Changes)

附注 (Additional Info)

自查清单 (Checklist)

在你认为本 PR 满足被审阅的标准之前，需要确保 / Before you mark the PR ready for review, please make sure that:

• 符合Venus项目管理规范中关于PR的相关标准 / The PR follows the PR standards set out in the Venus project management guidelines
• 具有清晰明确的commit message / All commits have a clear commit message.
• 包含相关的的测试用例或者不需要新增测试用例 / This PR has tests for new functionality or change in behaviour or not need to add new tests.
• 存在兼容性问题（接口, 配置，数据，灰度），如果存在需要进行文档说明 / This PR has compatibility issues (API, Configuration, Data, GrayRelease), if so, need to be documented.
• 包含相关的的指南以及文档或者不需要新增文档 / This PR has updated usage guidelines and documentation or not need
• 通过必要的检查项 / All checks are green

[codecov-commenter]

Codecov Report

Merging #6242 (f058c6e) into master (e926936) will increase coverage by 0%.
Report is 1 commits behind head on master.
The diff coverage is 77%.

Additional details and impacted files

@@          Coverage Diff           @@
##           master   #6242   +/-   ##
======================================
  Coverage      25%     25%           
======================================
  Files         636     636           
  Lines       78063   78015   -48     
======================================
+ Hits        20224   20255   +31     
+ Misses      55172   55094   -78     
+ Partials     2667    2666    -1     

[LinZexiao]

LGTM