chore(langchain): strip_ansi fucntion to remove ANSI escape sequences

[Chaitanya varma (pc099)]

Description:
Fixes a bug in the file callback test where ANSI escape codes were causing test failures. The improved test now properly handles ANSI escape sequences by:

• Using exact string comparison instead of substring checking
• Applying the strip_ansi function consistently to all file contents
• Adding descriptive assertion messages
• Maintaining test coverage and backward compatibility

The changes ensure tests pass reliably even when terminal control sequences are present in the output

Issue: Fixes #32150

Dependencies: None required - uses existing dependencies only.

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1 Skipped Deployment

Name	Status	Preview	Comments	Updated (UTC)
langchain	⬜️ Ignored (Inspect)	Visit Preview		Jul 25, 2025 3:51pm

[codspeed-hq]

CodSpeed WallTime Performance Report

Merging #32200 will improve performances by 16.29%

_{Comparing pc099:32150_terminal_char_fail (0e01d72) with master (0d6f915)}

⚠️ Unknown Walltime execution environment detected

Using the Walltime instrument on standard Hosted Runners will lead to inconsistent data.

For the most accurate results, we recommend using CodSpeed Macro Runners: bare-metal machines fine-tuned for performance measurement consistency.

Summary

⚡ 4 improvements
✅ 9 untouched benchmarks

Benchmarks breakdown

	Benchmark	BASE	HEAD	Change
⚡	test_import_time[CallbackManager]	482.2 ms	414.7 ms	+16.29%
⚡	test_import_time[LangChainTracer]	461.5 ms	411.7 ms	+12.08%
⚡	test_import_time[RunnableLambda]	261.6 ms	232.6 ms	+12.44%
⚡	test_import_time[Runnable]	255.5 ms	230.2 ms	+10.99%

[codspeed-hq]

CodSpeed Instrumentation Performance Report

Merging #32200 will not alter performance

_{Comparing pc099:32150_terminal_char_fail (0e01d72) with master (0d6f915)}

Summary

✅ 14 untouched benchmarks

[Eugene Yurtsev (eyurtsev)]

Sorry ignore me -- read over the original issue