Improve file-pattern target performance for GRIB

[sandorkertesz]

Description

Relates to #965

Contributor Declaration

By opening this pull request, I affirm the following:

• All authors agree to the Contributor License Agreement.
• The code follows the project's coding standards.
• I have performed self-review and added comments where needed.
• I have added or updated tests to verify that my changes are effective and functional.
• I have run all existing tests and confirmed they pass.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 85.29%. Comparing base (137ec91) to head (76bc989).
⚠️ Report is 8 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #974      +/-   ##
==========================================
- Coverage   85.31%   85.29%   -0.02%     
==========================================
  Files         184      184              
  Lines       14463    14473      +10     
  Branches      718      719       +1     
==========================================
+ Hits        12339    12345       +6     
- Misses       1919     1922       +3     
- Partials      205      206       +1     

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