Fix minimal basePath handling (#53174)

We no longer handle basePath stripping further down in minimal mode so
this prevents the re-adding we used to do.

Manually tested with
https://33-base-path-gsp-404-m8w6hhs1m-vtest314-ijjk-testing.vercel.app/docs/api/hello

Fixes: [slack
thread](https://vercel.slack.com/archives/C03F2CMNGKG/p1690309135573409)

packages/next/src/server/base-server.ts

@@ -930,9 +930,7 @@ export default abstract class Server<ServerOptions extends Options = Options> {
           for (const key of routeParamKeys) {
             delete parsedUrl.query[key]
           }
-          parsedUrl.pathname = `${this.nextConfig.basePath || ''}${
-            matchedPath === '/' && this.nextConfig.basePath ? '' : matchedPath
-          }`
+          parsedUrl.pathname = matchedPath
           url.pathname = parsedUrl.pathname
         } catch (err) {
           if (err instanceof DecodeError || err instanceof NormalizeError) {