[release-1.21] Bump cert-manager to v1.19.1

[mboersma]

What type of PR is this?

/kind cleanup

What this PR does / why we need it:

Manual cherry-pick of #5922.

Updates cert-manager to the current release v1.19.1 to sync with CAPI.

Which issue(s) this PR fixes:

N/A, but see #5910 for prior art.

Special notes for your reviewer:

TODOs:

• squashed commits
• includes documentation
• adds unit tests
• cherry-pick candidate

Release note:

NONE

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 46.93%. Comparing base (11c202f) to head (7780d61).
⚠️ Report is 3 commits behind head on release-1.21.

Additional details and impacted files

@@              Coverage Diff              @@
##           release-1.21    #5926   +/-   ##
=============================================
  Coverage         46.93%   46.93%           
=============================================
  Files               279      279           
  Lines             29687    29687           
=============================================
  Hits              13934    13934           
  Misses            14940    14940           
  Partials            813      813           

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[jackfrancis]

/lgtm
/approve

[k8s-ci-robot]

LGTM label has been added.

Git tree hash: 2bccf0ea0aa19e30f0828c134f931ee6d782c41d

[k8s-ci-robot]

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