chore: keep the pluginWrapper bean for compatibility

[guqing]

What type of PR is this?

/area core
/milestone 2.18.x

What this PR does / why we need it:

为了平滑升级先保留 PluginWrapper 的 Bean

Does this PR introduce a user-facing change?

None

[codecov]

Codecov Report

Attention: Patch coverage is 33.33333% with 2 lines in your changes missing coverage. Please review.

Project coverage is 58.21%. Comparing base (bc10336) to head (727fc4c).
Report is 63 commits behind head on main.

Files	Patch %	Lines
.../src/main/java/run/halo/app/plugin/BasePlugin.java	0.00%	2 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #6271      +/-   ##
============================================
+ Coverage     54.51%   58.21%   +3.70%     
- Complexity     3523     3759     +236     
============================================
  Files           646      647       +1     
  Lines         21862    21953      +91     
  Branches       1528     1541      +13     
============================================
+ Hits          11917    12779     +862     
+ Misses         9328     8554     -774     
- Partials        617      620       +3     

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[JohnNiang]

/lgtm

[f2c-ci-robot]

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