optimize: optimize fastjson deserialization

[slievrly]

• I have registered the PR changes.

Ⅰ. Describe what this PR did

optimize fastjson deserialization

Ⅱ. Does this pull request fix one issue?

Ⅲ. Why don't you add test cases (unit test/integration test)?

Ⅳ. Describe how to verify it

Ⅴ. Special notes for reviews

[codecov]

Codecov Report

Attention: Patch coverage is 58.33333% with 5 lines in your changes missing coverage. Please review.

Project coverage is 50.87%. Comparing base (62e7883) to head (9deded0).

Files	Patch %	Lines
...e/seata/integration/http/AbstractHttpExecutor.java	58.33%	5 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##                2.x    #6747      +/-   ##
============================================
- Coverage     51.04%   50.87%   -0.17%     
+ Complexity     5930     5915      -15     
============================================
  Files          1058     1058              
  Lines         36772    36779       +7     
  Branches       4368     4367       -1     
============================================
- Hits          18769    18713      -56     
- Misses        16109    16177      +68     
+ Partials       1894     1889       -5     

Files	Coverage Δ
...e/seata/integration/http/AbstractHttpExecutor.java	55.71% <58.33%> (+0.15%)	⬆️

... and 6 files with indirect coverage changes

[funky-eyes]

LGTM