[action] [PR:13404] Fix reference of variable for PR testing template

[mssonicbld]

Description of PR

Summary: Fixes # (issue)

Type of change

• [ ] Bug fix
• [ ] Testbed and Framework(new/improvement)
• [ ] Test case(new/improvement)

Back port request

• [ ] 202012
• [ ] 202205
• [ ] 202305
• [ ] 202311
• [ ] 202405

Approach

What is the motivation for this PR?

Fix reference of variable for PR testing template

How did you do it?

How did you verify/test it?

Any platform specific information?

Supported testbed topology if it's a new test case?

Documentation

[mssonicbld]

Original PR: https://github.com/sonic-net/sonic-mgmt/pull/13404

[wangxin]

This is not the right way to fix PR testing failures.