[ISSUE #10181] Remove lock when resetting offset in PopConsumerService

[lizhimins]

Which Issue(s) This PR Fixes

• Fixes [Enhancement] Some minor fixes in PopConsumerService #10181

Brief Description

How Did You Test This Change?

[codecov-commenter]

Codecov Report

❌ Patch coverage is 50.00000% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 48.86%. Comparing base (2b5e709) to head (cdeb9a4).

Files with missing lines	Patch %	Lines
...apache/rocketmq/broker/pop/PopConsumerService.java	50.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@              Coverage Diff              @@
##             develop   #10250      +/-   ##
=============================================
- Coverage      49.00%   48.86%   -0.14%     
+ Complexity     13462    13425      -37     
=============================================
  Files           1375     1375              
  Lines         100397   100394       -3     
  Branches       12965    12964       -1     
=============================================
- Hits           49195    49058     -137     
- Misses         45213    45319     +106     
- Partials        5989     6017      +28     

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[lollipopjin]

LGTM