otelslog, otelzap: align with code attributes semantic conventions

[pellared]

Why

Fixes #6869

Related to:

• clarify code function name semantic-conventions#1944
• Clarify values for code.function.name and code.namespace semantic-conventions#1677

What

• The code.function attribute emitted by the log bridges stores package path-qualified function name.
• The code.namespace attribute is no longer added.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 76.0%. Comparing base (053acd0) to head (8a9655a).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##            main   #6870     +/-   ##
=======================================
- Coverage   76.1%   76.0%   -0.1%     
=======================================
  Files        219     219             
  Lines      21315   21299     -16     
=======================================
- Hits       16226   16207     -19     
- Misses      4529    4531      +2     
- Partials     560     561      +1     

Files with missing lines	Coverage Δ
bridges/otelslog/handler.go	93.1% <100.0%> (-0.3%)	⬇️
bridges/otelzap/core.go	97.7% <100.0%> (-0.2%)	⬇️

... and 1 file with indirect coverage changes