Remove treesit-traverse functions

Remove treesit-traverse functions

Remove before adding the replacements.

* doc/lispref/parsing.texi (Retrieving Node): Remove relevant sections.
* lisp/treesit.el (treesit-traverse-depth-first)
(treesit--traverse-breadth-first-1)
(treesit-traverse-breadth-first)
(treesit-next-sibling-or-up)
(treesit-traverse-forward)
(treesit-search-forward)
(treesit-search-beginning):
(treesit-search-end): Remove functions.
(treesit-defun-query): Remove variable.
(treesit-beginning-of-defun)
(treesit-end-of-defun): Remove functions.
* test/src/treesit-tests.el: Remove comments.