fix: include_tracing_fields arg to control unvetted data in rust_tracing integration

[matt-codecov]

implemented my suggestion from #3778 so that if anton agrees we can merge this before the weekend

this PR renames the send_sensitive_data flag to include_tracing_fields. the data in question is generally data the user expects tracing to record or data they explicitly passed into a log statement to be recorded, so if we call it "sensitive" they may think we are referring to something else

also, this PR applies the same condition to both on_record() and on_new_span(). both callbacks set the same fields, so they should either both be redacted or both be allowed. previously only on_record() had the condition applied.

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 84.30%. Comparing base (4bec4a4) to head (10e3d9c).

✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3780      +/-   ##
==========================================
+ Coverage   84.26%   84.30%   +0.03%     
==========================================
  Files         137      137              
  Lines       14558    14561       +3     
  Branches     2459     2460       +1     
==========================================
+ Hits        12268    12275       +7     
+ Misses       1530     1528       -2     
+ Partials      760      758       -2     

Files with missing lines	Coverage Δ
sentry_sdk/integrations/rust_tracing.py	84.61% <100.00%> (+0.32%)	⬆️

... and 2 files with indirect coverage changes