Improved handling Google Service Account Approach in GitHub Actions ci

[JonathanLeeWH]

The current Approach

1. decrypt the encrypted secret file (An encrypted Google Service Account json file required for firebase) using a shell script
2. The decrypted Google Service Account json file is used

The new Approach

1. Instead of decrypting the encrypted secret file stored, use GitHub Secrets

To do

• To remove unnecessary environment variables such as GOOGLE_APPLICATION_CREDENTIALS
• To update all docker files and docker-compose files with the new approach and environmental variables
• To update the GitHub Actions workflow to use the new GitHub secrets environmental variables
• To update Readme.md documentation with the new environmental variables