feat(source/istio): reduce cpu cycles with indexers

[ivankatliarchuk]

What does it do ?

TODO:

• results from real clusters

This is a follow-up PR for #5536

• Added indexers to speed up lookups
• Added transfomers to reduce memory footprint

Before

BenchmarkEndpointTargetsFromServicesMedium-16                       	   11194	    105419 ns/op
BenchmarkEndpointTargetsFromServicesMediumIterateOverGateways
BenchmarkEndpointTargetsFromServicesMediumIterateOverGateways-16    	     290	   4070484 ns/op
BenchmarkEndpointTargetsFromServicesHigh
BenchmarkEndpointTargetsFromServicesHigh-16                         	      88	  12669344 ns/op
BenchmarkEndpointTargetsFromServicesHighIterateOverGateways
BenchmarkEndpointTargetsFromServicesHighIterateOverGateways-16      	       1	13425263466 ns/op

With the change

BenchmarkEndpointTargetsFromServicesMedium
BenchmarkEndpointTargetsFromServicesMedium-14                       	  586600	      2069 ns/op
BenchmarkEndpointTargetsFromServicesMediumIterateOverGateways
BenchmarkEndpointTargetsFromServicesMediumIterateOverGateways-14    	    5715	    210000 ns/op
BenchmarkEndpointTargetsFromServicesHigh
BenchmarkEndpointTargetsFromServicesHigh-14                         	  540793	      1881 ns/op
BenchmarkEndpointTargetsFromServicesHighIterateOverGateways
BenchmarkEndpointTargetsFromServicesHighIterateOverGateways-14      	       6	 192442562 ns/op

This are syntetic benchmarks. Same time the difference is 5x. So it should provide a potential improvement in terms of cpu cycles and processing times

Follow-up:

• move optimisations for istio source; example from pod service

  external-dns/source/pod.go

  Line 69 in 468fb66

  err := podInformer.Informer().AddIndexers(informers.IndexerWithOptions[*corev1.Pod](

  .
• do not make API call for ingresses, instead use caching/indexing/transformations

Motivation

PR #5473
Issue #5458
Potential why performance is poor description #5473 (comment)

More

• Yes, this PR title follows Conventional Commits
• Yes, I added unit tests
• Yes, I updated end user documentation accordingly

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[mloiseleur]

/lgtm

[ivankatliarchuk]

I'll block this. I think found a bug or issue that this approach may not work as expected

/hold

[ivankatliarchuk]

Great example of unit-tests all green, but reality is different. The case I found did not have any tests coverage.

[ivankatliarchuk]

Closing this for now. As current approach has some bugs

/close

[k8s-ci-robot]

@ivankatliarchuk: Closed this PR.

Details

In response to this:

Closing this for now. As current approach has some bugs

/close

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