Fixed NullPointerException in CommandUtil.fetchBrokerNameByAddr

[TheRealHaui]

Fixed NullPointerException in CommandUtil.fetchBrokerNameByAddr if address does not get found.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 0% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 48.28%. Comparing base (455305a) to head (6daf682).
⚠️ Report is 5 commits behind head on develop.

Files with missing lines	Patch %	Lines
...org/apache/rocketmq/tools/command/CommandUtil.java	0.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@              Coverage Diff              @@
##             develop    #9824      +/-   ##
=============================================
- Coverage      48.39%   48.28%   -0.11%     
+ Complexity     12259    12237      -22     
=============================================
  Files           1314     1314              
  Lines          93676    93777     +101     
  Branches       12013    12034      +21     
=============================================
- Hits           45331    45282      -49     
- Misses         42757    42874     +117     
- Partials        5588     5621      +33     

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