Fix style and unwinding code in treesit.c

Fix style and unwinding code in treesit.c

This was supposed to be a cherry-pick from master, but
isn't, due to the unnecessary rush to fix master without
cleaning up the mess first and without separating changes
that can and cannot be backported.
* src/treesit.c (treesit_traverse_cleanup_cursor): Fix indentation
style.
(Ftreesit_search_subtree, Ftreesit_search_forward)
(Ftreesit_induce_sparse_tree): Fix specpdl unwinding.  (Bug#62823)
Do not merge to master.