Experiment: replacing informers by watch API

[mariomac]

This is just a vibe-coded PoC. Informers have a big impact in the memory of each K8s cache instance. This PoC replaces them by the Watch API.

This is just a test to see if it passes all the tests, and a starting point for human review and later optimization/improvements.

[codecov]

Codecov Report

❌ Patch coverage is 41.31327% with 429 lines in your changes missing coverage. Please review.
✅ Project coverage is 20.98%. Comparing base (cd1d8df) to head (3bac195).

Files with missing lines	Patch %	Lines
pkg/kube/kubecache/meta/resource_watcher.go	32.27%	235 Missing and 21 partials ⚠️
pkg/kube/kubecache/meta/watch_manager.go	51.88%	101 Missing and 14 partials ⚠️
pkg/kube/kubecache/meta/watch_cache.go	43.82%	47 Missing and 3 partials ⚠️
pkg/kube/kubecache/meta/informers_init.go	58.82%	4 Missing and 3 partials ⚠️
pkg/kube/kubecache/meta/informers.go	87.50%	1 Missing ⚠️

❗ There is a different number of reports uploaded between BASE (cd1d8df) and HEAD (3bac195). Click for more details.

HEAD has 1 upload less than BASE

Flag	BASE (cd1d8df)	HEAD (3bac195)
unittests	1	0

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #1086       +/-   ##
===========================================
- Coverage   47.26%   20.98%   -26.29%     
===========================================
  Files         261      222       -39     
  Lines       27458    25622     -1836     
===========================================
- Hits        12979     5377     -7602     
- Misses      13611    19619     +6008     
+ Partials      868      626      -242     

Flag	Coverage Δ
integration-test	22.34% <0.00%> (-0.49%)	⬇️
integration-test-arm	0.00% <0.00%> (ø)
k8s-integration-test	3.64% <52.79%> (+0.99%)	⬆️
oats-test	0.00% <0.00%> (ø)
unittests	?

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[grcevski]

Looks like it worked :)