koord-scheduler: improve the readability of the PreFilter error message of the DeviceShare plugin

[jasonliu747]

Ⅰ. Describe what this PR does

Currently, the error message of PreFiltre in DeviceShare plugin cannot be understood intuitively.
This PR will improve the readability.

Ⅱ. Does this pull request fix one issue?

fix #840

Ⅲ. Describe how to verify it

Ⅳ. Special notes for reviews

V. Checklist

• I have written necessary docs and comments
• I have added necessary unit tests and integration tests
• All checks passed in make test

[codecov]

Codecov Report

Patch coverage: 100.00% and project coverage change: -0.02 ⚠️

Comparison is base (150d96e) 67.23% compared to head (81c3640) 67.22%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1077      +/-   ##
==========================================
- Coverage   67.23%   67.22%   -0.02%     
==========================================
  Files         255      255              
  Lines       28622    28622              
==========================================
- Hits        19243    19240       -3     
- Misses       8038     8040       +2     
- Partials     1341     1342       +1     

Flag	Coverage Δ
unittests	67.22% <100.00%> (-0.02%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
pkg/scheduler/plugins/deviceshare/utils.go	100.00% <100.00%> (ø)
pkg/util/httputil/reverseproxy.go	84.30% <0.00%> (-0.80%)	⬇️

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[eahydra]

/lgtm

[koordinator-bot]

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