#### What type of PR is this?

/kind bug
/area core
/milestone 2.21.x

#### What this PR does / why we need it:

This PR fixes the always show of ghost user in post contributors.

#### Which issue(s) this PR fixes:

Fixes https://github.com/halo-dev/halo/issues/7710

#### Does this PR introduce a user-facing change?

```release-note
修复文章贡献者中始终显示已删除用户的问题
```