refactor(@angular-devkit/build-angular): remove deprecation of namedChunks

Previusly this option didn't have an effect on platform server because when targetting commonjs all chunks will be concatenated into main.js.

We now changed the module to esnext, which enables us to have lazy loading on the server.

Author: alan-agius4

packages/angular_devkit/build_angular/src/server/schema.json

@@ -213,8 +213,7 @@
     "namedChunks": {
       "type": "boolean",
       "description": "Use file name for lazy loaded chunks.",
-      "default": true,
-      "x-deprecated": "Since version 9. This option has no effect on server platform."
+      "default": true
     },
     "bundleDependencies": {
       "description": "Which external dependencies to bundle into the bundle. By default, all of node_modules will be bundled.",