git_ui: Prevent button overflow due to long names (#25940)

- Fix component preview widths for git panel
- Fix buttons getting pushed off the screen in git  panel

Release Notes:

- N/A

---------

Co-authored-by: Mikayla Maki <mikayla.c.maki@gmail.com>

crates/title_bar/src/title_bar.rs

@@ -401,7 +401,7 @@ impl TitleBar {
                         .child(
                             Label::new(nickname.clone())
                                 .size(LabelSize::Small)
-                                .text_ellipsis(),
+                                .truncate(),
                         ),
                 )
                 .tooltip(move |window, cx| {