set PluginClassLoader for plugin config

[lilai23]

What type of PR is this?

Bug

What this PR does / why we need it?

Change all the classloaders for plugin config to Pluginclassloader

Which issue(s) this PR fixes？

Fixes #1464

Does this PR introduce a user-facing change?

No

Checklist

• Make sure there is a GitHub_issue related with this PR before you start working on it.
• Make sure you have squashed your change to one single commit.
• GitHub Actions works fine in this PR.

[codecov]

Codecov Report

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

Project coverage is 43.42%. Comparing base (d270273) to head (970fd59).
Report is 6 commits behind head on develop.

Files	Patch %	Lines
...ant/core/plugin/classloader/PluginClassLoader.java	0.00%	1 Missing ⚠️
...ermant/core/plugin/config/PluginConfigManager.java	0.00%	1 Missing ⚠️

Additional details and impacted files

@@              Coverage Diff              @@
##             develop    #1465      +/-   ##
=============================================
- Coverage      44.06%   43.42%   -0.64%     
+ Complexity      4712     4649      -63     
=============================================
  Files           1231     1231              
  Lines          26382    26381       -1     
  Branches        2755     2754       -1     
=============================================
- Hits           11624    11455     -169     
- Misses         13370    13549     +179     
+ Partials        1388     1377      -11     

Flag	Coverage Δ
unittests	43.42% <0.00%> (-0.64%)	⬇️

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