fix(python): Issue PerformanceWarning in LazyFrame.__contains__

[toroleapinc]

Summary

Add PerformanceWarning to LazyFrame.__contains__ to match the behavior of other LazyFrame properties (schema, columns, dtypes, width) that require resolving the schema.

Changes

• Added issue_warning() call with PerformanceWarning category in LazyFrame.__contains__
• Added test case for the new warning in test_lazyframe.py

Rationale

As noted in #21917, after #16964 all other methods on LazyFrame that might unexpectedly cause the schema to be resolved emit PerformanceWarning, except for __contains__. This was an oversight since 'col' in lf is functionally identical to 'col' in lf.columns which does emit the warning.

Fixes #21917

[orlp]

Did you follow the AI policy?

[toroleapinc]

Yes

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 81.67%. Comparing base (9d60226) to head (9f553de).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #26734      +/-   ##
==========================================
+ Coverage   81.00%   81.67%   +0.67%     
==========================================
  Files        1805     1805              
  Lines      248021   248022       +1     
  Branches     3132     3132              
==========================================
+ Hits       200902   202569    +1667     
+ Misses      46313    44647    -1666     
  Partials      806      806              

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