Remove `experimental: { serverActions: true } from examples as it is stable in next 14. (#57598)

Co-authored-by: Jiachi Liu <inbox@huozhi.im>

examples/next-forms/next.config.js

@@ -1,8 +1,4 @@
 /** @type {import('next').NextConfig} */
-const nextConfig = {
-  experimental: {
-    serverActions: true,
-  },
-}
+const nextConfig = {}
 
 module.exports = nextConfig

examples/with-fauna/next.config.js

@@ -1,7 +1,3 @@
-const nextConfig = {
-  experimental: {
-    serverActions: true,
-  },
-}
+const nextConfig = {}
 
 module.exports = nextConfig

examples/with-stripe-typescript/next.config.js

@@ -1,5 +1 @@
-module.exports = {
-  experimental: {
-    serverActions: true,
-  },
-}
+module.exports = {}