feat(config): combine default switches into mode

[slonka]

combine SkipMeshCreation SkipTenantResources and SkipHostnameGenerators into Mode

Motivation

Implementation information

Supporting documentation

Closes #12413

[github-actions]

Reviewer Checklist

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If something doesn't apply please check the box and add a justification if the reason is non obvious.

• Is the PR title satisfactory? Is this part of a larger feature and should be grouped using > Changelog?
• PR description is clear and complete. It Links to relevant issue as well as docs and UI issues
• This will not break child repos: it doesn't hardcode values (.e.g "kumahq" as an image registry)
• IPv6 is taken into account (.e.g: no string concatenation of host port)
• Tests (Unit test, E2E tests, manual test on universal and k8s)
  • Don't forget ci/ labels to run additional/fewer tests
• Does this contain a change that needs to be notified to users? In this case, UPGRADE.md should be updated.
• Does it need to be backported according to the backporting policy? (this GH action will add "backport" label based on these file globs, if you want to prevent it from adding the "backport" label use no-backport-autolabel label)

[lahabana]

1. There is a way to add deprecation warnings in the logs which we should probably leverage here.
2. be mindful of mink and CD and more generally backward compat
3. in k8s should we auto default to none and have the default stuff be part of the helm chart?

[slonka]

1. In config files it looks the same (word, "Deprecated" followed by ":"):

kuma/pkg/config/plugins/runtime/k8s/config.go

Lines 137 to 139 in 1f6f11b

	// Name of Service Account that is used to run the Control Plane
	// Deprecated: Use AllowedUsers instead.
	ServiceAccountName string `json:"serviceAccountName,omitempty" envconfig:"kuma_runtime_kubernetes_service_account_name"`

There is also a warning in Validate() function:

kuma/pkg/config/plugins/runtime/k8s/config.go

Lines 448 to 450 in 1f6f11b

	if c.ServiceAccountName != defaultServiceAccountName {
	logger.Info("[WARNING]: using deprecated configuration option - .ServiceAccountName, please use AllowedUsers.")
	}

So I assume it's about adding it in Validate() function.

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will respond to rest of the points in a later comment