otellogrus: set SeverityText field to logrus hook

[huiyifyj]

The Severity field is used to represent the severity of the log, but it can't replace human-readable level string,
the SeverityText ¹ field seems a optional field, as same as log level.

This PR is to set the SeverityText field based on the logrus.Level in the otellogrus hook.

Footnotes

1. OTEL Spec: Data Model for Logs #SeverityText ↩

[dmathieu]

This looks good, but it needs a changelog entry.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 81.5%. Comparing base (b72e8bc) to head (e2a0a7c).
Report is 1 commits behind head on main.

Additional details and impacted files

@@          Coverage Diff          @@
##            main   #7553   +/-   ##
=====================================
  Coverage   81.5%   81.5%           
=====================================
  Files        198     198           
  Lines      17976   17977    +1     
=====================================
+ Hits       14663   14664    +1     
  Misses      2916    2916           
  Partials     397     397           

Files with missing lines	Coverage Δ
bridges/otellogrus/hook.go	96.0% <100.0%> (+<0.1%)	⬆️

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[pellared]

This only needs a changelog entry.

[huiyifyj]

This only needs a changelog entry.

👌