If a user has modified the Mini Cart template part and the theme introduces a custom one, in the frontend the theme template takes precedence

[Aljullu]

To reproduce

1. With TT3, makes some edits to the Mini Cart template part and save it.
2. Verify the edits are visible in the frontend when you open the Mini Cart drawer.
3. Now, let's imagine the theme you are using releases an update which introduces a Mini Cart template part. To do so, create a mini-cart.html file in the parts subfolder of your theme.
4. In the editor, notice the customized template in step 1 takes priority over the theme one.
5. In the frontend, notice the theme template takes priority over the customized one.

Expected behavior

I would expect the template part I see in the frontend to be the same I see in the editor. Currently, it might happen that the editor and the frontend show different template parts, which is super-confusing and makes it impossible to introduce changes to the template part.

Regarding which template part should take preference, IMO it should be the user modified one. This seems to be how other WC template work. That means that, in the editor, we are displaying the correct template part, but in the frontend we aren't.

Screenshots

Editor	Frontend