Relax cluster tag requirement on subnets during auto-discovery

[kishorj]

Relax the kubernetes cluster tag requirement on subnets during auto-discovery. The prior behavior was to discover only those subnets with the tag kubernetes.io/cluster/<clustername> and values {owned, shared}. If there are subnets with the cluster tag, those still get choosen. In case there are multiple subnets per AZ, auto-discovery will break the tie in the following order

1. prefer subnets with the cluster tag kubernetes.io/cluster/
2. prefer the subnet that is first in lexicographic order

If the subnet has tag for a different cluster, auto-discovery will ignore such subnets.

Tests done

• subnets with cluster tag got choosen during auto discovery
• subnets got sorted in lexicographic order if there were ties
• subnets without cluster tags were also considered by auto-discovery
• subnets with tag for different cluster did not get auto-discovered

[k8s-ci-robot]

Hi @kishorj. Thanks for your PR.

I'm waiting for a kubernetes-sigs member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

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[codecov-io]

Codecov Report

Merging #1773 (0a1a724) into main (67494bd) will increase coverage by 0.15%.
The diff coverage is 96.00%.

@@            Coverage Diff             @@
##             main    #1773      +/-   ##
==========================================
+ Coverage   46.76%   46.91%   +0.15%     
==========================================
  Files         110      110              
  Lines        5988     6007      +19     
==========================================
+ Hits         2800     2818      +18     
- Misses       2925     2926       +1     
  Partials      263      263              

Impacted Files	Coverage Δ
pkg/networking/subnet_resolver.go	93.28% <96.00%> (+0.21%)	⬆️

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[kishorj]

/label tide/merge-method-squash

[M00nF1sh]

/ok-to-test

[M00nF1sh]

/lgtm

[M00nF1sh]

/test pull-aws-load-balancer-controller-e2e-test

[M00nF1sh]

/test pull-aws-load-balancer-controller-e2e-test

[M00nF1sh]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

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This pull-request has been approved by: kishorj, M00nF1sh

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