fix(explore): Restore muted empty state text

Preserve the previous secondary text color for traces table empty states.
Without the muted variant, the new Text primitive falls back to the
primary token and makes the empty state copy appear bolder.

Co-Authored-By: GPT-5.4 <noreply@openai.com>
Made-with: Cursor

Author: nsdeschenes

static/app/views/explore/tables/tracesTable/styles.tsx

@@ -134,7 +134,7 @@ export function EmptyStateText({
 }) {
   return (
     <Container>
-      <Text size={size} align={textAlign}>
+      <Text size={size} align={textAlign} variant="muted">
         {children}
       </Text>
     </Container>