improve readabillity in toolbox and corresponding tests

[heckstrahler]

No description provided.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[codecov]

Codecov Report

❌ Patch coverage is 92.30769% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 74.90%. Comparing base (de5a2ac) to head (fe979ac).
⚠️ Report is 1 commits behind head on develop.

Files with missing lines	Patch %	Lines
pandapower/toolbox/grid_modification.py	90.47%	2 Missing ⚠️
pandapower/toolbox/data_modification.py	75.00%	1 Missing ⚠️
pandapower/toolbox/element_selection.py	88.88%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #2771   +/-   ##
========================================
  Coverage    74.89%   74.90%           
========================================
  Files          315      315           
  Lines        36348    36347    -1     
========================================
+ Hits         27224    27225    +1     
+ Misses        9124     9122    -2     

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