…load from Google Drive during migration automation

Description:

This pull request introduces a pivotal enhancement to the GitHub environment's mechanism for downloading GA packs from Google Drive.

Changes Made:

Transition to Service Account JSON Credentials:

The method for accessing Google Drive has been revamped. Instead of using a GCP API key, we now leverage a Service Account to download files. This is a more secure approach to handle file downloads from Google Drive.
For this purpose, a dedicated file (creds.json) has been created to securely store the Service Account JSON credentials. This file is located within the .github/migration-tester/migration-automation directory.
Removal of Old GCP Credentials:

The older method of using the GCP API key, represented by the secrets GCP_CLIENT_ID, GCP_CLIENT_SECRET, and GCP_REFRESH_TOKEN, has been deprecated and removed from the workflow. This change aligns with the shift towards utilizing the Service Account for the file download operations.

made continue-on-error value to true.

Ensured secure removal of creds.json from .github/workflows.

Enhanced security by decoding sensitive JSON credentials directly from the environment variable and generating a JWT token for authentication. This eliminates the need to store credentials in a file.(creds.json)

The removal of the creds.json file was executed because this step has been superseded by the introduction of environment variables when using JSON credentials. This change prevents the storage of JSON credentials within a file, enhancing security.