Delete init.yml when toggling manually managed

[Balint-R]

Toggling manually managed should delete/recreate the init.yml file for site managed data. Currently, if there is data added both through the site interface and manually, the site data might be used even if manually managed is toggled.

The site data init.yml should also be deleted for all existing problems that have manually managed toggled on.

[FherStk]

This could break the init.yml files that include configs that are not supported by the frontend, be aware of that, please.