ci: fix go cache key

[zhangzujian]

• Make sure you have followed Kube-OVN Code Style.

What type of this PR

• CI

Which issue(s) this PR fixes:

Fixes #(issue-number)

WHAT

🤖 Generated by Copilot at 2746c04

This change improves the scheduled e2e workflow by fixing the branch handling logic. It simplifies the workflow for the default branches and adds the necessary steps for the non-default branches in .github/workflows/scheduled-e2e.yaml.

🤖 Generated by Copilot at 2746c04

Oh we are the e2e testers, we run the tests on kube-ovn
We check out different branches, to see what's going on
We don't need the default ones, we've got them in our sights
But we need the non-default ones, to fix them up all right

HOW

🤖 Generated by Copilot at 2746c04

• Fix the branch checkout steps for the scheduled e2e workflow (link, link, link, link, link, link)