fix(medusa): add estimate count to admin products (#12467)

what:
 * Add `estimate_count` property to `/admin/products` endpoint when index engine FF is on

packages/medusa/src/api/admin/products/route.ts

@@ -80,6 +80,7 @@ async function getProductsWithIndexEngine(
   res.json({
     products: products.map(remapProductResponse),
     count: metadata!.estimate_count,
+    estimate_count: metadata!.estimate_count,
     offset: metadata!.skip,
     limit: metadata!.take,
   })