Fix some visual bugs w/ edit predictions (#24591)

* correct the size of key binding icons
* avoid spurious modifier in 'jump to edit' popover when already
previewing
* fix height of the edit preview popover

Release Notes:

- N/A

Co-authored-by: agu-z <hi@aguz.me>

crates/ui/src/components/keybinding_hint.rs

@@ -199,7 +199,7 @@ impl RenderOnce for KeybindingHint {
                         blur_radius: px(0.),
                         spread_radius: px(0.),
                     }])
-                    .child(self.keybinding.size(kb_size)),
+                    .child(self.keybinding.size(rems_from_px(kb_size.0))),
             )
             .children(self.suffix)
     }