[ISSUE 8230]fix the acl for NotifyClientTerminationRequest because group can be null

[dingshuangxi888]

…ull.

Which Issue(s) This PR Fixes

Fixes #8230

Brief Description

How Did You Test This Change?

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 25.00000% with 3 lines in your changes are missing coverage. Please review.

Project coverage is 42.88%. Comparing base (89c1509) to head (30127b8).
Report is 21 commits behind head on develop.

Files	Patch %	Lines
...apache/rocketmq/acl/plain/PlainAccessResource.java	0.00%	2 Missing ⚠️
...on/builder/DefaultAuthorizationContextBuilder.java	50.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@              Coverage Diff              @@
##             develop    #8231      +/-   ##
=============================================
- Coverage      42.93%   42.88%   -0.05%     
+ Complexity     10387    10369      -18     
=============================================
  Files           1270     1270              
  Lines          88693    88726      +33     
  Branches       11401    11408       +7     
=============================================
- Hits           38079    38053      -26     
- Misses         45925    45966      +41     
- Partials        4689     4707      +18     

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[drpmma]

LGTM