ruff - enable and fix ISC, implicit string concatenation

[pavoljuhas]

• Enable ruff rule ISC for implicit string concatenation
• Fix word-break across concatenated strings
• ruff - fix ISC - implicit string concatenation issues
• also fix pytest warning on always-matching empty pattern

No change in the effective code.

Partially implements #7505

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[mhucka]

This is nice.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.68%. Comparing base (cb60bba) to head (c1a6fcc).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #7511      +/-   ##
==========================================
- Coverage   98.68%   98.68%   -0.01%     
==========================================
  Files        1091     1091              
  Lines       96948    96948              
==========================================
- Hits        95673    95669       -4     
- Misses       1275     1279       +4     

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[pavoljuhas]

This is nice.

Thanks! (inspired by 33188d9)