Fix static workers distributing (#50194)

This removes the `computeWorkerKey` from our static workers as this
doesn't work in practice as efficiently as we hoped since a single page
can have thousands of paths to render which won't be distributed to
separate workers if the same worker key is returned.

Fixes: #49593

**Before**

![before](https://github.com/vercel/next.js/assets/22380829/da1e0a03-8b15-42a6-a2ac-6e4ff29c350d)


**After**

![after](https://github.com/vercel/next.js/assets/22380829/b27354f6-bcdb-4cad-888c-7d6b143e0ee2)

packages/next/src/build/index.ts

@@ -1189,20 +1189,6 @@ export default async function build(
             },
           },
           enableWorkerThreads: config.experimental.workerThreads,
-          computeWorkerKey(method, ...args) {
-            if (method === 'exportPage') {
-              const typedArgs = args as Parameters<
-                typeof import('./worker').exportPage
-              >
-              return typedArgs[0].pathMap.page
-            } else if (method === 'isPageStatic') {
-              const typedArgs = args as Parameters<
-                typeof import('./worker').isPageStatic
-              >
-              return typedArgs[0].originalAppPath || typedArgs[0].page
-            }
-            return method
-          },
           exposedMethods: sharedPool
             ? [
                 'hasCustomGetInitialProps',