Learning track UI strings on ToC landing pages too (#45711)

Co-authored-by: Hector Alfaro <hectorsector@github.com>

src/landings/pages/product.tsx

@@ -127,6 +127,9 @@ export const getServerSideProps: GetServerSideProps<Props> = async (context) =>
     additionalUINamespaces.push('product_guides')
   } else if (relativePath?.endsWith('index.md')) {
     props.tocLandingContext = getTocLandingContextFromRequest(req)
+    if (props.tocLandingContext.currentLearningTrack?.trackName) {
+      additionalUINamespaces.push('learning_track_nav')
+    }
   } else {
     // All articles that might have hover cards needs this
     additionalUINamespaces.push('popovers')