Fix invalid dom nesting error and remove redundant braces (#10115)

Fixes a console log about invalid dom nesting:

<img width="1256" alt="image"
src="https://github.com/user-attachments/assets/0849103c-6901-4b64-a124-00eaf8cc7dde"
/>

I've changed the offending div to a span. We set `display: flex` on it,
anyway, so it shouldn't make a difference.

I've also removed some redundant functions and braces that we don't
need.

frontend/src/component/feature/FeatureStrategy/FeatureStrategyMenu/FeatureStrategyMenu.tsx

@@ -217,11 +217,10 @@ export const FeatureStrategyMenu = ({
                 maxWidth='md'
                 PaperProps={{
                     sx: {
-                        borderRadius: (theme) => '12px',
+                        borderRadius: '12px',
                     },
                 }}
             >
-                {
                 <FeatureStrategyMenuCards
                     projectId={projectId}
                     featureId={featureId}
@@ -238,7 +237,6 @@ export const FeatureStrategyMenu = ({
                     }}
                     onClose={onClose}
                 />
-                }
             </Dialog>
             {selectedTemplate && (
                 <ReleasePlanReviewDialog

frontend/src/component/feature/FeatureStrategy/FeatureStrategyMenu/FeatureStrategyMenuCards/FeatureStrategyMenuCards.tsx

@@ -91,7 +91,7 @@ const StyledInfoIcon = styled(InfoOutlinedIcon)(({ theme }) => ({
     color: theme.palette.text.secondary,
 }));
 
-const StyledIcon = styled('div')(({ theme }) => ({
+const StyledIcon = styled('span')(({ theme }) => ({
     width: theme.spacing(3),
     '& > svg': {
         fill: theme.palette.primary.main,