Minor updates & cleanup

All Submissions:

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• [YES] Have you added an explanation of what your changes do and why you'd like us to include them?
• [YES] I have updated the documentation accordingly.
• [YES] My code follows the code style of this project.

Current Behavior or Linked Issues

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1. As we removed flag keda_v2_enabled - it makes sense to cleanup all related docs and tfvar files
2. It will be good to configure this output to point to module.istio_appgateway.name instead module.appgateway.name
3. It will be good to move task: Cache@2 into the "tasks/tests-unit.yml" template and add a condition for it (so we follow the same pattern as it is done in "tasks/tests-int.yml")

Does this introduce a breaking change?

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• [NO]

Other information

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