chore(pkg/gc): don't rely on core.Now var for time

[lahabana]

• Always provide ticker as a parameter to both finalizer and gc
• Use the time of the ticker instead of core.Now()
• Rewrite tests to create synthetic ticks
• Improve logging

Motivation:

• Tests would have to rely mutexes and some would expose a race because
  of the shared global variable. .e.g: https://app.circleci.com/pipelines/gh/kumahq/kuma/16160/workflows/e5332335-a44e-451f-8942-51a8909156bf/jobs/213638
• We can write very precise tests as we trigger the ticks ourselves
• Not relying on global vars is always an improvement

Signed-off-by: Charly Molter charly.molter@konghq.com

Checklist prior to review

• Link to docs PR or issue --
• Link to UI issue or PR --
• Is the issue worked on linked? --
• The PR does not hardcode values that might break projects that depend on kuma (e.g. "kumahq" as a image registry) --
• The PR will work for both Linux and Windows, system specific functions like syscall.Mkfifo have equivalent implementation on the other OS --
• Unit Tests --
• E2E Tests --
• Manual Universal Tests --
• Manual Kubernetes Tests --
• Do you need to update UPGRADE.md? --
• Does it need to be backported according to the backporting policy? --
• Do you need to explicitly set a > Changelog: entry here?

[bartsmykla]

lgtm

[codecov-commenter]

Codecov Report

Merging #4918 (76a5a49) into master (3f201b1) will decrease coverage by 0.00%.
The diff coverage is 71.42%.

@@            Coverage Diff             @@
##           master    #4918      +/-   ##
==========================================
- Coverage   46.68%   46.68%   -0.01%     
==========================================
  Files         687      687              
  Lines       46656    46655       -1     
==========================================
- Hits        21781    21779       -2     
  Misses      22966    22966              
- Partials     1909     1910       +1     

Impacted Files	Coverage Δ
pkg/gc/components.go	0.00% <0.00%> (ø)
pkg/gc/finalizer.go	78.26% <75.00%> (ø)
pkg/gc/collector.go	63.41% <77.77%> (ø)
pkg/plugins/leader/postgres/leader_elector.go	82.97% <0.00%> (-6.39%)	⬇️
pkg/xds/generator/direct_access_proxy_generator.go	90.90% <0.00%> (+1.13%)	⬆️

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