Improvement: replace tree

[maksymvavilov]

We have a tree tooling to deal with endpoints. Since we got rid of the ACM, endpoints on the record will always form a tree with a single branch. It makes no sense to overcomplicate the logic that deals with endpoints.
The only scenario when the tree is useful is if we parse endpoints from a zone (that includes endpoints from other controllers) but it seems redundant: we should trust other controllers to keep their chains linked.
Replacing the tree with a leaf search should suffice.

[maksymvavilov]

It depends on #293 as we might be using the tree properly after it is done