Add SRv6 test cases on 7 nodes testbed

[eddieruan-alibaba]

Description of PR

This PR is to add some SRv6 test cases listed in https://github.com/sonic-net/sonic-mgmt/blob/master/docs/testplan/srv6/SRv6-phoenixwing-ptf-testplan.md. These test cases are running on the 7 node testbed.

The infra changes are in https://github.com/sonic-net/sonic-mgmt/pull/15349

Summary: Fixes # (issue)

Type of change

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

Back port request

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

Approach

What is the motivation for this PR?

Add couple SRv6 Test cases listed in https://github.com/sonic-net/sonic-mgmt/blob/master/docs/testplan/srv6/SRv6-phoenixwing-ptf-testplan.md.

How did you do it?

Add 5 more test cases, including ptf traffic test and link flapping test cases.

How did you verify/test it?

Via daily jenkins run

The test log could be found at http://phoenixwing.com.cn/vsonic

Any platform specific information?

Only on 7 node vsonic testbed.

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

Documentation

https://github.com/sonic-net/sonic-mgmt/blob/master/docs/testplan/srv6/SRv6-phoenixwing-ptf-testplan.md

[wangxin]

Can you fix the PR title and description?

[eddieruan-alibaba]

Can you fix the PR title and description?

Done