[ISSUE #9978] Remove static from loadJsonConfig and unify exception s…

[yx9o]

Fixes #9978 .

[codecov-commenter]

Codecov Report

❌ Patch coverage is 0% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 48.73%. Comparing base (1117ab8) to head (3b5a0b0).

Files with missing lines	Patch %	Lines
...rg/apache/rocketmq/proxy/config/Configuration.java	0.00%	6 Missing ⚠️

Additional details and impacted files

@@              Coverage Diff              @@
##             develop    #9979      +/-   ##
=============================================
- Coverage      48.85%   48.73%   -0.12%     
+ Complexity     12769    12739      -30     
=============================================
  Files           1324     1324              
  Lines          96405    96407       +2     
  Branches       12434    12434              
=============================================
- Hits           47094    46985     -109     
- Misses         43568    43658      +90     
- Partials        5743     5764      +21     

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