Further nightlies cleanup (#53302)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/53302

Those files can also go as they've been moved to
https://github.com/react-native-community/nightly-tests

Changelog:
[Internal] [Changed] -

Reviewed By: cipolleschi

Differential Revision: D80342950

fbshipit-source-id: 0b5cc8f424eefa00c48377fe2fbc2cca5e7ef48d

.github/workflows/check-nightly.yml

@@ -1,38 +0,0 @@
-# This jobs runs every day 2 hours after the nightly job and its purpose is to report
-# a failure in case the nightly failed to be published. We are going to hook this to an internal automation.
-name: Check Nightlies
-
-on:
-  workflow_dispatch:
-  # nightly build @ 4:15 AM UTC
-  schedule:
-    - cron: '15 4 * * *'
-
-jobs:
-  check-nightly:
-    runs-on: ubuntu-latest
-    if: github.repository == 'facebook/react-native'
-    steps:
-      - name: Checkout
-        uses: actions/checkout@v4
-      - name: Check nightly
-        run: |
-          TODAY=$(date "+%Y%m%d")
-          echo "Checking nightly for $TODAY"
-          NIGHTLY="$(npm view react-native | grep $TODAY)"
-          if [[ -z $NIGHTLY ]]; then
-            echo 'Nightly job failed.'
-            exit 1
-          else
-            echo 'Nightly Worked, All Good!'
-          fi
-
-  test-libraries:
-    uses: ./.github/workflows/test-libraries-on-nightlies.yml
-    needs: check-nightly
-    secrets:
-      discord_webhook_url: ${{ secrets.NIGHTLY_DISCORD_WEBHOOK }}
-      firebase_app_email: ${{ secrets.FIREBASE_APP_EMAIL }}
-      firebase_app_pass: ${{ secrets.FIREBASE_APP_PASS }}
-      firebase_app_projectname: ${{ secrets.FIREBASE_APP_PROJECTNAME }}
-      firebase_app_apikey: ${{ secrets.FIREBASE_APP_APIKEY }}