chore(react-router): remove unused code (#13761)

Author: MichaelDeBoey

packages/react-router/__tests__/server-runtime/utils.ts

@@ -1,5 +1,3 @@
-import prettier from "prettier";
-
 import type { FutureConfig } from "../../lib/dom/ssr/entry";
 import type {
   ServerRoute,
@@ -119,11 +117,3 @@ export function mockServerBuild(
     ),
   };
 }
-
-export function prettyHtml(source: string): string {
-  return prettier.format(source, { parser: "html" });
-}
-
-export function isEqual<A, B>(
-  arg: A extends B ? (B extends A ? true : false) : false
-): void {}