Fix the problem of not being able to autowire settingFetcher bean in plugin

[JohnNiang]

What type of PR is this?

/kind bug
/area core
/area plugin

What this PR does / why we need it:

The problem was introduced by PR #6141. That PR wrongly registered settingFetcher singleton bean.

Which issue(s) this PR fixes:

Does this PR introduce a user-facing change?

None

[ruibaby]

/lgtm

[f2c-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: ruibaby

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• OWNERS [ruibaby]

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[f2c-ci-robot]

New changes are detected. LGTM label has been removed.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.

Project coverage is 56.98%. Comparing base (bc10336) to head (bde459d).
Report is 4 commits behind head on main.

Files	Patch %	Lines
...plugin/DefaultPluginApplicationContextFactory.java	0.00%	2 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #6156      +/-   ##
============================================
+ Coverage     54.51%   56.98%   +2.47%     
- Complexity     3523     3706     +183     
============================================
  Files           646      652       +6     
  Lines         21862    22038     +176     
  Branches       1528     1537       +9     
============================================
+ Hits          11917    12559     +642     
+ Misses         9328     8874     -454     
+ Partials        617      605      -12     

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