@rollup/plugin-replace: specify preventAssignment: true (#33329)

This is to fix a warning since the option will be set to true in the next major version of the plugin

js/tests/integration/rollup.bundle.js

@@ -12,7 +12,8 @@ module.exports = {
   },
   plugins: [
     replace({
-      'process.env.NODE_ENV': '"production"'
+      'process.env.NODE_ENV': '"production"',
+      preventAssignment: true
     }),
     nodeResolve(),
     babel({

js/tests/karma.conf.js

@@ -77,7 +77,8 @@ const conf = {
   rollupPreprocessor: {
     plugins: [
       replace({
-        'process.env.NODE_ENV': '"dev"'
+        'process.env.NODE_ENV': '"dev"',
+        preventAssignment: true
       }),
       istanbul({
         exclude: [