SSL expiration metrics cannot be tied to dynamic updates

[aledbf]

What this PR does / why we need it:

Which issue this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close that issue when PR gets merged):

fixes #4158

Special notes for your reviewer:

[codecov-io]

Codecov Report

Merging #4160 into master will increase coverage by 0.01%.
The diff coverage is 0%.

@@            Coverage Diff             @@
##           master    #4160      +/-   ##
==========================================
+ Coverage   57.67%   57.68%   +0.01%     
==========================================
  Files          87       87              
  Lines        6459     6459              
==========================================
+ Hits         3725     3726       +1     
+ Misses       2306     2304       -2     
- Partials      428      429       +1

Impacted Files	Coverage Δ
internal/ingress/controller/controller.go	46.56% <0%> (ø)	⬆️
internal/watch/file_watcher.go	84.61% <0%> (+3.84%)	⬆️

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[ElvinEfendi]

/lgtm

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: aledbf, ElvinEfendi

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