gpui: Rename rounded_md to rounded_sm (#26228)

This PR renames the `rounded_md` style method to `rounded_sm`.

Follow up to https://github.com/zed-industries/zed/pull/26221, which
freed up the `rounded_sm` name.

Release Notes:

- N/A

crates/ui/src/components/button/button_like.rs

@@ -509,9 +509,9 @@ impl RenderOnce for ButtonLike {
                 this.w(width).justify_center().text_center()
             })
             .when_some(self.rounding, |this, rounding| match rounding {
-                ButtonLikeRounding::All => this.rounded_md(),
-                ButtonLikeRounding::Left => this.rounded_l_md(),
-                ButtonLikeRounding::Right => this.rounded_r_md(),
+                ButtonLikeRounding::All => this.rounded_sm(),
+                ButtonLikeRounding::Left => this.rounded_l_sm(),
+                ButtonLikeRounding::Right => this.rounded_r_sm(),
             })
             .gap(DynamicSpacing::Base04.rems(cx))
             .map(|this| match self.size {