Deploy to the primary production Heroku App via Actions (#21807)

* Update the production deployment workflow to target the main Heroku app

Without exposing our internal Heroku app name!

* Refactor the staging deployment script a bit to match more closely

* Use the HEROKU_PRODUCTION_APP_NAME Secret in the workflow

* Add a note about the newly required environment variable for production deployment into the local deploy script

* Add critical errors if the HEROKU_PRODUCTION_APP_NAME is missing

* Extract HEROKU_PRODUCTION_APP_NAME from process.env

.github/workflows/prod-build-deploy.yml

@@ -133,13 +133,20 @@ jobs:
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
           HEROKU_API_TOKEN: ${{ secrets.HEROKU_API_TOKEN }}
+          HEROKU_PRODUCTION_APP_NAME: ${{ secrets.HEROKU_PRODUCTION_APP_NAME }}
           HYDRO_ENDPOINT: ${{ secrets.HYDRO_ENDPOINT }}
           HYDRO_SECRET: ${{ secrets.HYDRO_SECRET }}
           SOURCE_BLOB_URL: ${{ steps.build-source.outputs.download_url }}
           DELAY_FOR_PREBOOT: 'true'
         with:
           script: |
-            const { GITHUB_TOKEN, HEROKU_API_TOKEN, SOURCE_BLOB_URL, DELAY_FOR_PREBOOT } = process.env
+            const {
+              GITHUB_TOKEN,
+              HEROKU_API_TOKEN,
+              HEROKU_PRODUCTION_APP_NAME,
+              SOURCE_BLOB_URL,
+              DELAY_FOR_PREBOOT
+            } = process.env
 
             // Exit if GitHub Actions PAT is not found
             if (!GITHUB_TOKEN) {
@@ -151,6 +158,11 @@ jobs:
               throw new Error('You must supply a HEROKU_API_TOKEN environment variable!')
             }
 
+            // Exit if Heroku App name is not found
+            if (!HEROKU_PRODUCTION_APP_NAME) {
+              throw new Error('You must supply a HEROKU_PRODUCTION_APP_NAME environment variable!')
+            }
+
             // Workaround to allow us to load ESM files with `require(...)`
             const esm = require('esm')
             require = esm({})