adminscore: fix null arg to str_replace

[agoujot]

Bug: T410809

[codecov]

Codecov Report

❌ Patch coverage is 0% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 69.46%. Comparing base (4b8eb28) to head (02c13be).
⚠️ Report is 201 commits behind head on main.

Files with missing lines	Patch %	Lines
src/Model/AdminScore.php	0.00%	4 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main     #588      +/-   ##
============================================
- Coverage     71.30%   69.46%   -1.85%     
- Complexity     1275     1327      +52     
============================================
  Files            46       46              
  Lines          3792     3926     +134     
============================================
+ Hits           2704     2727      +23     
- Misses         1088     1199     +111     

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