feat: improved tracing for courier

[alnr]

No description provided.

[aeneasr]

Seems to fail some tests now: https://github.com/ory/kratos/actions/runs/12031094979/job/33540061865?pr=4226#step:14:69

[aeneasr]

@alnr could you fix the build please?

[codecov]

Codecov Report

Attention: Patch coverage is 94.11765% with 2 lines in your changes missing coverage. Please review.

Project coverage is 78.57%. Comparing base (d9f6f75) to head (4004927).
Report is 4 commits behind head on master.

Files with missing lines	Patch %	Lines
courier/smtp_channel.go	95.45%	0 Missing and 1 partial ⚠️
identity/extension_verification.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4226      +/-   ##
==========================================
- Coverage   78.61%   78.57%   -0.05%     
==========================================
  Files         381      381              
  Lines       27318    27346      +28     
==========================================
+ Hits        21476    21486      +10     
- Misses       4223     4237      +14     
- Partials     1619     1623       +4     

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