fix(python): Fix LazyFrame.__contains__ not issuing PerformanceWarning

[magikcarp]

Closes #21917

Changes

• Make LazyFrame.__contains__ emit PerformanceWarning and redirection of user to use collect_schema() to mirror other methods that causes the schema to be collected.
• Update tests to call collect_schema() directly to prevent emitting the PerformanceWarning.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 1 line in your changes missing coverage. Please review.

Project coverage is 80.78%. Comparing base (69ad1ba) to head (7c244b9).

Files with missing lines	Patch %	Lines
py-polars/polars/lazyframe/frame.py	0.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #22236   +/-   ##
=======================================
  Coverage   80.78%   80.78%           
=======================================
  Files        1639     1639           
  Lines      235548   235549    +1     
  Branches     2714     2714           
=======================================
+ Hits       190278   190294   +16     
+ Misses      44630    44614   -16     
- Partials      640      641    +1     

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