ci(addons): log in to quay.io with the existing registry credentials

The add-on publish read ADDON_OCI_USERNAME and ADDON_OCI_PASSWORD, which are
not set, so the publish failed at login with 'Username and password
required'. Point it at the quayUsername and quayPassword secrets the backend
and image workflows already use.

Assisted-by: Claude:claude-sonnet-5-5 [Claude Code]
Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

.github/workflows/addons-package.yml

@@ -292,8 +292,8 @@ jobs:
         uses: docker/login-action@v4
         with:
           registry: ${{ needs.plan.outputs.registry }}
-          username: ${{ secrets.ADDON_OCI_USERNAME }}
-          password: ${{ secrets.ADDON_OCI_PASSWORD }}
+          username: ${{ secrets.quayUsername }}
+          password: ${{ secrets.quayPassword }}
       - name: Push the platform digests and the index
         id: push
         env:
@@ -383,8 +383,8 @@ jobs:
         uses: docker/login-action@v4
         with:
           registry: ${{ needs.plan.outputs.registry }}
-          username: ${{ secrets.ADDON_OCI_USERNAME }}
-          password: ${{ secrets.ADDON_OCI_PASSWORD }}
+          username: ${{ secrets.quayUsername }}
+          password: ${{ secrets.quayPassword }}
       - name: Move the aliases
         env:
           ALIASES: ${{ needs.plan.outputs.aliases }}