fix: plugin self tab extension point not working when no setting definition

[ruibaby]

What type of PR is this?

/area console
/kind bug
/milestone 2.10.x

What this PR does / why we need it:

修复当插件没有设置表单定义时，详情选项卡扩展点不生效的问题。

Which issue(s) this PR fixes:

Fixes #4633

Special notes for your reviewer:

可以通过以下插件进行测试：

1. plugin-migrate-1.2.0-SNAPSHOT.jar.zip
2. https://github.com/halo-dev/plugin-app-store/releases/tag/v1.0.0-alpha.4
3. https://github.com/halo-dev/plugin-s3

Does this PR introduce a user-facing change?

修复当插件没有设置表单定义时，详情选项卡扩展点不生效的问题。

[codecov]

Codecov Report

Merging #4659 (1968bdb) into main (5fa0056) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##               main    #4659   +/-   ##
=========================================
  Coverage     60.98%   60.98%           
  Complexity     2610     2610           
=========================================
  Files           378      378           
  Lines         13551    13551           
  Branches        959      959           
=========================================
  Hits           8264     8264           
  Misses         4822     4822           
  Partials        465      465           

[guqing]

/lgtm

[JohnNiang]

/approve

[f2c-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: JohnNiang

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• console/OWNERS [JohnNiang]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment