Fix tree-sitter tests

Fix tree-sitter tests

After 2ce27563ecc, treesit--navigate-things takes a TACTIC argument
instead of using treesit-defun-tactic, so the tests need to change
from binding treesit-defun-tactic to passing the tactic argument,
which is what this change does.

* test/src/treesit-tests.el:
(treesit--ert-insert-and-parse-marker): New argument TACTIC.
(treesit-defun-navigation-nested-1)
(treesit-defun-navigation-nested-2)
(treesit-defun-navigation-nested-3)
(treesit-defun-navigation-top-level): Pass TACTIC argument.