chore: add missing tracing in manager_cookie.go

[jonas-jonas]

Related issue(s)

Checklist

• I have read the contributing guidelines.
• I have referenced an issue containing the design document if my change
  introduces a new feature.
• I am following the
  contributing code guidelines.
• I have read the security policy.
• I confirm that this pull request does not address a security
  vulnerability. If this pull request addresses a security vulnerability, I
  confirm that I got the approval (please contact
  [email protected]) from the maintainers to push
  the changes.
• I have added tests that prove my fix is effective or that my feature
  works.
• I have added or changed the documentation.

Further Comments

[hperl]

Yes, please :)

[codecov]

Codecov Report

Merging #3615 (ae93cf3) into master (912dccd) will increase coverage by 0.00%.
Report is 1 commits behind head on master.
The diff coverage is 89.47%.

❗ Current head ae93cf3 differs from pull request most recent head e98583d. Consider uploading reports for the commit e98583d to get more accurate results

@@           Coverage Diff           @@
##           master    #3615   +/-   ##
=======================================
  Coverage   78.29%   78.30%           
=======================================
  Files         342      342           
  Lines       23395    23402    +7     
=======================================
+ Hits        18317    18324    +7     
  Misses       3699     3699           
  Partials     1379     1379           

Files	Coverage Δ
continuity/manager_cookie.go	54.16% <89.47%> (+4.93%)	⬆️