Remove NewPlanPresenter class

What does this MR do and why?

Related to #422537 (closed) (this comment particularly)

This MR removes the Subscriptions::NewPlanPresenter class that is not used any longer. It also adjusts calling logic accordingly.

How to set up and validate locally

Passing pipeline should be enough here.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #422537 (closed)