[ISSUE #8248]fix: getTotalBatchMaxBytes return holdSize

[humkum]

Fixes #8248

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 42.88%. Comparing base (949991e) to head (c3ee1c1).

Files	Patch %	Lines
...e/rocketmq/client/producer/ProduceAccumulator.java	0.00%	1 Missing :warning:

Additional details and impacted files

@@              Coverage Diff              @@
##             develop    #8249      +/-   ##
=============================================
- Coverage      42.91%   42.88%   -0.04%     
+ Complexity     10380    10368      -12     
=============================================
  Files           1271     1271              
  Lines          88783    88783              
  Branches       11408    11408              
=============================================
- Hits           38102    38071      -31     
- Misses         45982    46005      +23     
- Partials        4699     4707       +8     

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[humkum]

@guyinyou @RongtongJin Please help to review this pr