chore: Deprecate max_spans LangChain parameter

[alexander-alderman-webb]

Description

Set the default value for max_spans option of LangchainIntegration to None, so that langchain spans are not exited early by default.

Deprecate the option as well, announcing its removal in the next major.

Issues

Closes #4985
Closes PY-1914

Reminders

• Please add tests to validate your changes, and lint your code using tox -e linters.
• Add GH Issue ID & Linear ID (if applicable)
• PR title should use conventional commit style (feat:, fix:, ref:, meta:)
• For external contributors: CONTRIBUTING.md, Sentry SDK development docs, Discord community

[linear]

PY-1918 Remove span description truncation in Redis

[codecov]

Codecov Report

❌ Patch coverage is 37.50000% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 84.02%. Comparing base (3bc1d17) to head (c371521).
⚠️ Report is 3 commits behind head on master.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
sentry_sdk/integrations/langchain.py	37.50%	3 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5074      +/-   ##
==========================================
+ Coverage   79.25%   84.02%   +4.76%     
==========================================
  Files         180      180              
  Lines       18023    18026       +3     
  Branches     3205     3207       +2     
==========================================
+ Hits        14284    15146     +862     
+ Misses       2856     1905     -951     
- Partials      883      975      +92     

Files with missing lines	Coverage Δ
sentry_sdk/integrations/langchain.py	68.49% <37.50%> (+0.21%)	⬆️

... and 25 files with indirect coverage changes

[linear]

PY-1914 Remove `max_spans` from `LangchainIntegration`