feat(python): Mark min_periods as keyword-only for rolling methods

[stinodego]

Closes #16684

This aligns the rolling_* and rolling_*_by methods. This is not breaking as the methods are marked as unstable.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 81.43%. Comparing base (ddf8126) to head (61ebd76).
Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #16738      +/-   ##
==========================================
- Coverage   81.45%   81.43%   -0.02%     
==========================================
  Files        1413     1413              
  Lines      186096   186183      +87     
  Branches     2776     2776              
==========================================
+ Hits       151588   151622      +34     
- Misses      33988    34041      +53     
  Partials      520      520              

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