editor: Fix panics in CursorPosition::update_position (#41237)

Fixes a regression introduced in
https://github.com/zed-industries/zed/pull/39857. As for the exact
reason this causes this issue I am not yet sure will investigate (as per
the todos in code)

Fixes ZED-23R

Release Notes:

- N/A *or* Added/Fixed/Improved ...

crates/sum_tree/src/sum_tree.rs

@@ -3,7 +3,7 @@ mod tree_map;
 
 use arrayvec::ArrayVec;
 pub use cursor::{Cursor, FilterCursor, Iter};
-use rayon::prelude::*;
+use rayon::iter::{IndexedParallelIterator, IntoParallelIterator, ParallelIterator as _};
 use std::marker::PhantomData;
 use std::mem;
 use std::{cmp::Ordering, fmt, iter::FromIterator, sync::Arc};