fix: atomic flush incorrect use and clean up code

[lizhanhui]

Which Issue(s) This PR Fixes

to #8829

Brief Description

How Did You Test This Change?

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 9.49367% with 143 lines in your changes missing coverage. Please review.

Project coverage is 47.38%. Comparing base (4f5f705) to head (979d4d0).

Files with missing lines	Patch %	Lines
...rocketmq/common/config/AbstractRocksDBStorage.java	0.00%	68 Missing ⚠️
...rg/apache/rocketmq/common/config/ConfigHelper.java	0.00%	65 Missing ⚠️
...e/rocketmq/common/config/ConfigRocksDBStorage.java	0.00%	10 Missing ⚠️

Additional details and impacted files

@@              Coverage Diff              @@
##             develop    #8830      +/-   ##
=============================================
- Coverage      47.51%   47.38%   -0.14%     
+ Complexity     11631    11599      -32     
=============================================
  Files           1283     1284       +1     
  Lines          90009    90017       +8     
  Branches       11584    11585       +1     
=============================================
- Hits           42771    42656     -115     
- Misses         42008    42110     +102     
- Partials        5230     5251      +21     

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