fix: NPE when adding a new service port

[leon-inf]

fix #8802

[codecov]

Codecov Report

Attention: Patch coverage is 85.71429% with 2 lines in your changes missing coverage. Please review.

Project coverage is 64.67%. Comparing base (b5d3380) to head (1b99d53).
Report is 1 commits behind head on release-0.9.

Files with missing lines	Patch %	Lines
controllers/apps/transformer_cluster_service.go	85.71%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@               Coverage Diff               @@
##           release-0.9    #8819      +/-   ##
===============================================
+ Coverage        64.44%   64.67%   +0.23%     
===============================================
  Files              359      359              
  Lines            46381    46387       +6     
===============================================
+ Hits             29889    30003     +114     
+ Misses           13807    13712      -95     
+ Partials          2685     2672      -13     

Flag	Coverage Δ
unittests	64.67% <85.71%> (+0.23%)	⬆️

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