[patch] [engg]: Revert changes to use token provided by GitHub

[juan-arias]

Proposed changes

This reverts PR #2864

Type of change

• Feature work
• Bug fix
• Documentation
• Engineering change
• Test
• Logging/Telemetry

Risk

• High – Errors could cause MAJOR regression of many scenarios. (Example: new large features or high level infrastructure changes)
• Medium – Errors could cause regression of 1 or more scenarios. (Example: somewhat complex bug fixes, small new features)
• Small – No issues are expected. (Example: Very small bug fixes, string changes, or configuration settings changes)

Additional information

This pull request makes minor updates to the GitHub Actions workflow for AI-powered issue auto-replies. The changes primarily adjust permissions and update the authentication token used in the workflow.

• Workflow permissions update:

  • Added the models: read permission to the workflow, allowing access to GitHub's models API.

• Authentication token update:

  • Changed the token used for authentication from GH_COPILOT_PAT_MODELS to the default GITHUB_TOKEN, simplifying credential management.