testsuite: remove deprecated manual cleanup in create_cmd_test

[ai-man-codes]

Manual cleanup is not needed anymore because of #9185 already being implemented.
So we can remove the #8980 code.

I have checked everything with the /tmp folder, the generated files are cleaned up safely after a test.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 75.93%. Comparing base (7ef2c25) to head (e19a221).
⚠️ Report is 8 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #9294      +/-   ##
==========================================
+ Coverage   75.88%   75.93%   +0.05%     
==========================================
  Files          86       86              
  Lines       14761    14771      +10     
  Branches     2198     2199       +1     
==========================================
+ Hits        11201    11216      +15     
+ Misses       2886     2879       -7     
- Partials      674      676       +2     

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[ThomasWaldmann]

Thanks!