Fixed building Admin in development mode for browser tests

- I switched over `build` to run in production mode because we now do
  `lerna run build` during the release process, but this was bundling
  development assets
- this adds `build:dev` and switches the browser test to use that, so
  they should use the development assets moving forwards

.github/workflows/browser-tests.yml

@@ -63,7 +63,7 @@ jobs:
     - name: Build Admin
       if: env.ENVIRONMENT == 'browser-tests-local'
       working-directory: ghost/admin
-      run: yarn build --silent
+      run: yarn build:dev
 
     - name: Run Playwright tests on a remote site
       if: env.ENVIRONMENT == 'browser-tests-staging'

ghost/admin/package.json

@@ -18,7 +18,7 @@
   "scripts": {
     "start": "ember serve",
     "build": "ember build --environment=production --silent",
-    "build:prod": "yarn build",
+    "build:dev": "yarn build --environment=development",
     "test:unit": "true",
     "test": "ember exam --split 2 --parallel",
     "lint:js": "eslint . --cache",