refactor: replace hasBorder with plain

Author: greatertomi

src/design-system/summary-expander/summary-expander.component.tsx

@@ -19,7 +19,7 @@ export type Props = OmitClassName<'button'> &
     title: string;
     disabled?: boolean;
     testId?: string;
-    hasBorder?: boolean;
+    plain?: boolean;
   }>;
 
 export const SummaryExpander = ({
@@ -29,7 +29,7 @@ export const SummaryExpander = ({
   disabled,
   testId,
   children,
-  hasBorder = true,
+  plain = false,
   ...props
 }: Readonly<Props>): JSX.Element => {
   return (
@@ -45,7 +45,7 @@ export const SummaryExpander = ({
         justifyContent="space-between"
         className={classNames(cx.header, {
           [cx.expanded]: open,
-          [cx.noBorder]: !hasBorder,
+          [cx.noBorder]: plain,
         })}
       >
         <Text.Body.Normal weight="$semibold" data-testid="expander-title">