Fix including Debug CSS in the index template

[belen-albeza]

This replicates the behavior when we were building the app with Gulp, in which the debug CSS was only included in local development.

• 💄 Reformat JS file and remove leftover code
• 🐛 Include debug css in local dev only

To test:

1. Run the devenv and wait for the frontend-watch and frontend-shadow tabs to finish their jobs.
   2.grep for text/css in the resources/public/index.html file. Two <link> tags for CSS files should be included, one of them should be debug.css

$ cat resources/public/index.html | grep css
<link id="theme" href="css/main.css?ts=1715957540350" rel="stylesheet" type="text/css" />
<link href="css/debug.css?ts=1715957540350" rel="stylesheet" type="text/css" />

3. Now with Ctrl+C stop the jobs in the frontend-watch and frontend-shadow tabs.
4. Change to the frontend directory and build the app for production:

cd frontend
./scripts/build

5. Check with grep that only a single CSS file is included in <link> tags in target/dist/index.html

cat target/dist/index.html | grep css
<link id="theme" href="css/main.css?ts=1715957714143" rel="stylesheet" type="text/css" />