opt: migration: set premigration to 90 minute

[simlecode]

关联的Issues (Related Issues)

https://github.com/filecoin-project/lotus/pull/11396/files

改动 (Proposed Changes)

预升级时间调整为 90 分钟

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 #6217 (4da82a7) into release/v1.14 (bc969f0) will decrease coverage by 1%.
Report is 5 commits behind head on release/v1.14.
The diff coverage is 3%.

Additional details and impacted files

@@              Coverage Diff              @@
##           release/v1.14   #6217   +/-   ##
=============================================
- Coverage             24%     23%   -1%     
=============================================
  Files                679     679           
  Lines              84190   84210   +20     
=============================================
  Hits               20210   20210           
- Misses             61315   61337   +22     
+ Partials            2665    2663    -2     

[LinZexiao]

LGTM