improve the sorting rules for themes side posts using publishTime

[longjuan]

What type of PR is this?

/kind improvement /area core

What this PR does / why we need it:

Provide administrators with the ability to adjust the order of articles by modifying the publish time.

Which issue(s) this PR fixes:

Fixes https://github.com/halo-dev/halo/issues/3143

Special notes for your reviewer:

修改前： 修改后：

Does this PR introduce a user-facing change?

主题侧文章以发布时间排序

[f2c-ci-robot[bot]]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: JohnNiang

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