feat(openai-agents): Truncate long messages

[alexander-alderman-webb]

Description

Cherry-picked from #5049

Issues

Closes TET-1208

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]

TET-1208 Python SDK: truncate gen_ai messages

[codecov]

Codecov Report

❌ Patch coverage is 77.77778% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 83.97%. Comparing base (98e3148) to head (aea824a).
⚠️ Report is 7 commits behind head on master.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
...k/integrations/openai_agents/spans/invoke_agent.py	75.00%	0 Missing and 1 partial ⚠️
sentry_sdk/integrations/openai_agents/utils.py	80.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5141      +/-   ##
==========================================
+ Coverage   83.94%   83.97%   +0.02%     
==========================================
  Files         180      180              
  Lines       18198    18205       +7     
  Branches     3231     3233       +2     
==========================================
+ Hits        15276    15287      +11     
+ Misses       1931     1924       -7     
- Partials      991      994       +3     

Files with missing lines	Coverage Δ
...k/integrations/openai_agents/spans/invoke_agent.py	86.11% <75.00%> (-1.77%)	⬇️
sentry_sdk/integrations/openai_agents/utils.py	89.77% <80.00%> (-0.71%)	⬇️

... and 3 files with indirect coverage changes