fix: remove unnecessary console in isDynamicPostpone (#69457)

### What?

Remove `console.log(err)` in `isDynamicPostpone`, I think this should be
a debug console that was accidentally left behind.

### Why?

This will cause meaningless logs to appear in the console when we use
the `unstable_rethrow` API.

Co-authored-by: JJ Kasper <jj@jjsweb.site>

packages/next/src/server/app-render/dynamic-rendering.ts

@@ -280,7 +280,6 @@ function createPostponeReason(route: string, expression: string) {
 }
 
 export function isDynamicPostpone(err: unknown) {
-  console.log(err)
   if (
     typeof err === 'object' &&
     err !== null &&