Fix get_workflow_job_id to dynamically get the repo name (#83036)
This helps testing on pytorch-canary, which has a different repo name. The different name fails the get_workflow_job_id step there because the canary PR refers to run ID and canary runner name, for example:
https://github.com/pytorch/pytorch-canary/runs/7735191886?check_suite_focus=true
Pull Request resolved: https://github.com/pytorch/pytorch/pull/83036
Approved by: https://github.com/zengk95
