feat: certifier otel metrics

[gk-kindred]

Introduces the following Otel metrics in talos certifier

// Capture the time from initiator got the request to certify at the cohort till the `Candidate` arrived on certifier
talos_initiator_certifier_candidate_received

// Capture the time from the `Candidate` arrived on certifier to `Decision` created
talos_initiator_certifier_decision_created

// Capture the time from the `Candidate` arrived on certifier to `Decision` published.
talos_initiator_certifier_decision_published

// Capture the time from initiator got the request to certify at the cohort till the `Decision` was created on certifier
talos_certifier_candidate_received_decision_created

// Capture the time from initiator got the request to certify at the cohort till the `Decision` was published on certifier.
talos_certifier_candidate_received_decision_published

[codecov]

Codecov Report

❌ Patch coverage is 73.07692% with 21 lines in your changes missing coverage. Please review.
✅ Project coverage is 66.53%. Comparing base (81b2279) to head (337db1d).
⚠️ Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
packages/talos_certifier/src/otel.rs	0.00%	20 Missing ⚠️
...talos_certifier_adapters/src/certifier_kafka_pg.rs	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #155      +/-   ##
==========================================
+ Coverage   66.30%   66.53%   +0.23%     
==========================================
  Files         123      124       +1     
  Lines       12149    12195      +46     
==========================================
+ Hits         8055     8114      +59     
+ Misses       4094     4081      -13     

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[simonol1]

Looks good to me - no write access