feat: rm isunseal method in gateway / 移除 unsesal 方法

[LinZexiao]

关联的Issues (Related Issues)

ref #5873

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 #5875 (2e3f39f) into master (d3b695c) will decrease coverage by 1%.
The diff coverage is 0%.

Additional details and impacted files

@@          Coverage Diff           @@
##           master   #5875   +/-   ##
======================================
- Coverage      24%     24%   -1%     
======================================
  Files         643     643           
  Lines       77812   77801   -11     
======================================
- Hits        19394   19390    -4     
+ Misses      55829   55823    -6     
+ Partials     2589    2588    -1     

[simlecode]

lgtm