fix: incorrect truncation of CSS resource reads

[guqing]

What type of PR is this?

/kind bug
/area core
/milestone 2.10.x

What this PR does / why we need it:

修复插件 css bundle 内容被错误拆分导致无法加载的问题

Which issue(s) this PR fixes:

Fixes #4677

Does this PR introduce a user-facing change?

修复插件 css bundle 内容被错误拆分导致无法加载的问题

[codecov]

Codecov Report

Merging #4678 (d269fa5) into main (3edf863) will decrease coverage by 0.03%.
Report is 1 commits behind head on main.
The diff coverage is 0.00%.

@@             Coverage Diff              @@
##               main    #4678      +/-   ##
============================================
- Coverage     61.75%   61.73%   -0.03%     
  Complexity     2781     2781              
============================================
  Files           402      402              
  Lines         14579    14584       +5     
  Branches       1011     1011              
============================================
  Hits           9003     9003              
- Misses         5087     5092       +5     
  Partials        489      489              

Files	Coverage Δ
...core/extension/service/impl/PluginServiceImpl.java	63.47% <0.00%> (-2.89%)	⬇️

[LIlGG]

/lgtm

[ruibaby]

/lgtm

[f2c-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: LIlGG, ruibaby

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:

• OWNERS [ruibaby]

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