[Test Gap][decap][t0] Add testcase to verify the decap rules are working after warm-reboot

[lolyu]

Test Gap Description

No testcase to validate the decap rules are created/working as expected after warm-reboot.

Note: This particular test case can be covered in dedicated upgrade path test.

Test Plan

1. verify the decap rules are present and IPinIP traffic could be decapsulated before warm reboot
2. warm reboot to a newer version
3. verify the decap rules are present and IPinIP traffic could be decapsulated after warm reboot

Test environment

No response

Attach files (if any)

No response