Updated test scripts for v2 apps

[ijlee2]

Background

In ijlee2/embroider-css-modules#247, I needed to update the test script so that tests will pass on ember-source@7.0.0.

It's important to note that NODE_ENV (process.env.NODE_ENV) and modes are two different concepts. Here's how different commands affect the NODE_ENV and mode:

Command	NODE_ENV	Mode
vite build	"production"	"production"
vite build --mode development	"production"	"development"
NODE_ENV=development vite build	"development"	"production"
NODE_ENV=development vite build --mode development	"development"	"development"

https://vite.dev/guide/env-and-mode#node-env-and-modes