fix: don't include prerendered routes in default generateManifest (#9471)

fixes #9463
bug was introduced in #8740

Author: dummdidumm

.changeset/old-teachers-shout.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/kit': patch
+---
+
+fix: don't include prerendered routes in default generateManifest

packages/kit/src/core/adapt/builder.js

@@ -162,7 +162,7 @@ export function create_builder({
 				relative_path: relativePath,
 				routes: subset
 					? subset.map((route) => /** @type {import('types').RouteData} */ (lookup.get(route)))
-					: route_data
+					: route_data.filter((route) => prerender_map.get(route.id) !== true)
 			});
 		},