WIP chore(source): istio informers index service objects

[ivankatliarchuk]

What does it do ?

note; to review after release

Indexers are way waster then listers, the difference could be 10x times with a cost of +~10% memory usage(for indexes)

Motivation

• previous PR perf(source): benchmarks on EndpointTargetsFromServices #5536
• previous PR chore(source): move cache informer to dedicated folder #5466
• opened PR add workerCount config and multiple worker supports for istio_gateway and istio_virtualservice #5473 (comment)

TODO:

• share syntetic results
• share results for real cluster

More

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

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by:
Once this PR has been reviewed and has the lgtm label, please assign raffo for approval. For more information see the Code Review Process.

The full list of commands accepted by this bot can be found here.

Needs approval from an approver in each of these files:

• OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[k8s-ci-robot]

PR needs rebase.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.