Investigate implication of user vs system managed identity

[aionic]

Using a user-managed identity decouples the lifecycle of the identity from the resources using it. Does it simplify the deployment, or improve performance to move everything to a user-managed identity, or should we just keep it system to align the lifecycle.

Todo: Determine our ultimate approach

Ref: https://docs.microsoft.com/en-us/azure/active-directory/managed-identities-azure-resources/managed-identity-best-practice-recommendations#choosing-system-or-user-assigned-managed-identities