feat: fewer DB loads when linking credentials, add tracing

[alnr]

No description provided.

[codecov]

Codecov Report

Attention: Patch coverage is 65.00000% with 7 lines in your changes missing coverage. Please review.

Project coverage is 78.62%. Comparing base (85a7071) to head (08620cb).
Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
selfservice/flow/login/hook.go	62.50%	2 Missing and 1 partial ⚠️
selfservice/strategy/oidc/strategy.go	62.50%	2 Missing and 1 partial ⚠️
selfservice/strategy/oidc/strategy_settings.go	75.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4252      +/-   ##
==========================================
+ Coverage   78.61%   78.62%   +0.01%     
==========================================
  Files         381      381              
  Lines       27372    27380       +8     
==========================================
+ Hits        21518    21528      +10     
  Misses       4233     4233              
+ Partials     1621     1619       -2     

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