fix: map KongConsumer to respective KongConsumerGroup in Konnect

[programmer04]

What this PR does / why we need it:

KIC 3.0.3 was the last without feature gate SanitizeKonnectConfigDumps=true by default (everything works as expected).

For newer versions mapping of KongConsumers to respective KongConsumersGroup is broken because the code responsible for sanitization omits consumer groups by mistake.

This field is crucial for proper mapping, see how the config is generated

kubernetes-ingress-controller/internal/dataplane/deckgen/generate.go

Lines 152 to 166 in ff2a3d9

	for _, c := range k8sState.Consumers {
	consumer := file.FConsumer{Consumer: c.Consumer}
	// If a consumer with no username and no custom_id is provided deck wont be able to process it,
	// but we shouldn't fail the rest of the deckgen either or this will result in one bad consumer
	// being capable of stopping all updates to the Kong Admin API.
	// This shouldn't happen as we enforce either of those field being present in CRD CEL validation rules.
	if consumer.Username == nil && consumer.CustomID == nil {
	logger.Error(nil, "Invalid consumer received (username and custom_id were empty)")
	continue
	}
	for _, cg := range c.ConsumerGroups {
	consumer.Groups = append(consumer.Groups, &cg)
	}

Which issue this PR fixes:

fixes #7143

PR Readiness Checklist:

Complete these before marking the PR as ready to review:

• the CHANGELOG.md release notes have been updated to reflect any significant (and particularly user-facing) changes introduced by this PR

[team-k8s-bot]

E2E (targeted) tests with KIND-based clusters were started at https://github.com/Kong/kubernetes-ingress-controller/actions/runs/13417500743

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 79.0%. Comparing base (d4d18a4) to head (ff2a3d9).
Report is 80 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##            main   #7144     +/-   ##
=======================================
+ Coverage   76.9%   79.0%   +2.1%     
=======================================
  Files        214     213      -1     
  Lines      25169   24977    -192     
=======================================
+ Hits       19356   19746    +390     
+ Misses      4794    4202    -592     
- Partials    1019    1029     +10     

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