Remove unused MON_* credentials (#1304)

## Description:

Remove unused MON_* credentials

## Please complete the following:

- [x] I have added screenshots for all UI updates
- [x] I process any text displayed to the user through translateText()
and I've added it to the en.json file
- [x] I have added relevant tests to the test directory
- [x] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced
- [x] I understand that submitting code with bugs that could have been
caught through manual testing blocks releases and new features for all
contributors

.github/workflows/deploy.yml

@@ -112,8 +112,6 @@ jobs:
           DOCKER_USERNAME: ${{ vars.DOCKERHUB_USERNAME }}
           ENV: ${{ inputs.target_domain == 'openfront.io' && 'prod' || 'staging' }}
           HOST: ${{ github.event_name == 'workflow_dispatch' && inputs.target_host || 'staging' }}
-          MON_PASSWORD: ${{ secrets.MON_PASSWORD }}
-          MON_USERNAME: ${{ secrets.MON_USERNAME }}
           OTEL_ENDPOINT: ${{ secrets.OTEL_ENDPOINT }}
           OTEL_PASSWORD: ${{ secrets.OTEL_PASSWORD }}
           OTEL_USERNAME: ${{ secrets.OTEL_USERNAME }}