Update Tiltfile to differentiate between aks and kind cluster

[nawazkh]

Tiltfile uses if "aks" in settings.get("kustomize_substitutions", {}).get("MGMT_CLUSTER_NAME", ""): to check if the tilt is being used with AKS cluster as a management cluster.
This is an inefficient approach. Especially when a user is switching from AKS -> KIND.

Suggested approach:

• We want to have a local env based approach that gets set whenever make ads-create is called; and unset that env variable whenever make kind-create is called.
• Once a similar logic is implemented, we want to update all the occurrences of if "aks" in settings.get("kustomize_substitutions", {}).get("MGMT_CLUSTER_NAME", ""): in the Tiltfile and use the env variable to check if it is a AKS cluster that is being used as a management cluster.