Only apply scroll correction in uniform_list when already scrolled (#3687)

This PR fixes an issue where the scroll correction added to the uniform
list in a35fdf45fc was being applied even
if the list wasn't scrolled at all.

This manifested in the project panel starting with an incorrect scroll
offset that would disappear once scrolled.

It seems like we should only need to apply this scroll correction when
the list is already scrolled.

Release Notes:

- N/A

crates/gpui2/src/elements/uniform_list.rs

@@ -206,7 +206,9 @@ impl Element for UniformList {
                             let content_height =
                                 item_height * self.item_count + padding.top + padding.bottom;
                             let min_scroll_offset = padded_bounds.size.height - content_height;
-                            if scroll_offset.y < min_scroll_offset {
+                            let is_scrolled = scroll_offset.y != px(0.);
+
+                            if is_scrolled && scroll_offset.y < min_scroll_offset {
                                 shared_scroll_offset.borrow_mut().y = min_scroll_offset;
                                 scroll_offset.y = min_scroll_offset;
                             }