Revert "app router: ensure static prefetch renders loading.js (#55950)"

This reverts commit ca57258.

Author: ztanner

packages/next/src/server/app-render/app-render.tsx

@@ -1122,9 +1122,7 @@ export const renderToHTMLOrFlight: AppPageRender = (
                 getDynamicParamFromSegment,
                 query
               ),
-              isPrefetch &&
-              !Boolean(components.loading) &&
-              !hasLoadingComponentInTree(loaderTree)
+              isPrefetch && !Boolean(components.loading)
                 ? null
                 : // Create component tree using the slice of the loaderTree
                   // @ts-expect-error TODO-APP: fix async component type
@@ -1147,9 +1145,7 @@ export const renderToHTMLOrFlight: AppPageRender = (
 
                     return <Component />
                   }),
-              isPrefetch &&
-              !Boolean(components.loading) &&
-              !hasLoadingComponentInTree(loaderTree)
+              isPrefetch && !Boolean(components.loading)
                 ? null
                 : (() => {
                     const { layoutOrPagePath } =

test/e2e/app-dir/app/app/linking/about/loading.js

@@ -18,7 +18,7 @@ createNextDescribe(
         ).toBeTruthy()
         expect(
           await next.readFile('.next/server/app/linking/about.prefetch.rsc')
-        ).toContain('About loading...')
+        ).toBeTruthy()
         expect(
           await next.readFile(
             '.next/server/app/dashboard/deployments/breakdown.prefetch.rsc'