chore: Bump Rust version to 1.86 (#28021)

Closes #ISSUE

Release Notes:

- N/A

crates/vim/src/motion.rs

@@ -2174,7 +2174,7 @@ fn matching(map: &DisplaySnapshot, display_point: DisplayPoint) -> DisplayPoint
 // https://neovim.io/doc/user/motion.html#N%25
 fn go_to_percentage(map: &DisplaySnapshot, point: DisplayPoint, count: usize) -> DisplayPoint {
     let total_lines = map.buffer_snapshot.max_point().row + 1;
-    let target_line = (count * total_lines as usize + 99) / 100;
+    let target_line = (count * total_lines as usize).div_ceil(100);
     let target_point = DisplayPoint::new(
         DisplayRow(target_line.saturating_sub(1) as u32),
         point.column(),

crates/vim/src/test/neovim_backed_test_context.rs

@@ -147,7 +147,7 @@ impl NeovimBackedTestContext {
             .name()
             .expect("thread is not named")
             .split(':')
-            .last()
+            .next_back()
             .unwrap()
             .to_string();
         Self {
@@ -171,7 +171,7 @@ impl NeovimBackedTestContext {
             .name()
             .expect("thread is not named")
             .split(':')
-            .last()
+            .next_back()
             .unwrap()
             .to_string();
         Self {