chore: revert playground counter and rollup config changes

Remove test private method from counter component and revert
playground rollup config back to default lwc() options.

Made-with: Cursor

Author: a-chabot

playground/rollup.config.js

@@ -21,7 +21,7 @@ export default (args) => {
                 'process.env.NODE_ENV': JSON.stringify(__ENV__),
                 preventAssignment: true,
             }),
-            lwc({ enablePrivateMethods: true }),
+            lwc(),
             args.watch &&
                 serve({
                     open: false,

playground/src/modules/x/counter/counter.js

@@ -7,13 +7,8 @@ export default class extends LightningElement {
 
     increment() {
         this.counter++;
-        this.#privateMethod();
     }
     decrement() {
         this.counter--;
     }
-
-    #privateMethod() {
-        this.counter++;
-    }
 }