Set expiration time for GCP runner secrets

[thehejik]

What does this PR do?

There was about 8000 Managed Secrets on GCP created by various GCP runners which costs money.

• This PR will set Expiration time by --ttl=18000s for newly created secrets so they will be auto removed after 5h.

• Added line for deleting GHREPO secret which was missing

Checklist:

• [x] GitHub Actions (if applicable) https://github.com/rancher/hosted-providers-e2e/actions/runs/11178220140