chore(issue-stream): Reduce font size of title and message (#79378)

Reduces the font size of the title and message of issues on the issue
stream.

Before: 

<img width="1994" alt="image"
src="https://github.com/user-attachments/assets/0d27529a-0c20-49be-a368-71814aaab58a">

After:

<img width="1996" alt="image"
src="https://github.com/user-attachments/assets/84b79069-cfd8-43aa-8d99-8ea4de4fa5ff">

static/app/components/eventOrGroupTitle.tsx

@@ -90,12 +90,14 @@ const Message = styled('span')`
   height: 100%;
   color: ${p => p.theme.textColor};
   font-weight: ${p => p.theme.fontWeightNormal};
+  font-size: ${p => p.theme.fontSizeMedium};
 `;
 
 const Title = styled('span')`
   ${p => p.theme.overflowEllipsis};
   display: inline-block;
   color: ${p => p.theme.textColor};
+  font-size: ${p => p.theme.fontSizeMedium};
 `;
 
 const Wrapper = styled('span')<{hasNewLayout: boolean}>`