Fix integration-tests by not using browserlist from root

The `browserlist`-config was introduced in 6bc73fdad7.

See https://webpack.js.org/configuration/target/#browserslist.

tests/integration/webpack-babel-test/webpack.config.js

@@ -11,6 +11,7 @@ testFiles
 module.exports = {
   entry: entryPoints,
   mode: 'production',
+  target: 'web',
   output: {
     filename: '[name]',
     path: __dirname + '/dist',

tests/integration/webpack-test/webpack.config.js

@@ -11,6 +11,7 @@ testFiles
 module.exports = {
   entry: entryPoints,
   mode: 'production',
+  target: 'web',
   output: {
     filename: '[name]',
     path: __dirname + '/dist',