Remove unused variable distinguish_unstaged_diff_hunks (#25462)

Release Notes:

- N/A

crates/editor/src/editor.rs

@@ -695,7 +695,6 @@ pub struct Editor {
     show_git_blame_inline: bool,
     show_git_blame_inline_delay_task: Option<Task<()>>,
     git_blame_inline_tooltip: Option<WeakEntity<crate::commit_tooltip::CommitTooltip>>,
-    distinguish_unstaged_diff_hunks: bool,
     git_blame_inline_enabled: bool,
     serialize_dirty_buffers: bool,
     show_selection_menu: Option<bool>,
@@ -1408,7 +1407,6 @@ impl Editor {
             custom_context_menu: None,
             show_git_blame_gutter: false,
             show_git_blame_inline: false,
-            distinguish_unstaged_diff_hunks: false,
             show_selection_menu: None,
             show_git_blame_inline_delay_task: None,
             git_blame_inline_tooltip: None,
@@ -12736,10 +12734,6 @@ impl Editor {
         });
     }
 
-    pub fn set_distinguish_unstaged_diff_hunks(&mut self) {
-        self.distinguish_unstaged_diff_hunks = true;
-    }
-
     pub fn expand_all_diff_hunks(
         &mut self,
         _: &ExpandAllDiffHunks,

crates/git_ui/src/project_diff.rs

@@ -127,7 +127,6 @@ impl ProjectDiff {
                 window,
                 cx,
             );
-            diff_display_editor.set_distinguish_unstaged_diff_hunks();
             diff_display_editor.set_expand_all_diff_hunks(cx);
             diff_display_editor.register_addon(GitPanelAddon {
                 workspace: workspace.downgrade(),