Add VRRP tests

[SerhiyBoikoPLV]

• test_vrrp_basic_on[bridge]
• test_vrrp_basic_on[port]
• test_vrrp_priority_on[bridge]
• test_vrrp_priority_on[port]
• test_vrrp_basic_down_on[bridge]
• test_vrrp_basic_down_on[port]

Also, updated cleanup functions, since they should not care whether DUTs have any links to TG.

Signed-off-by: Serhiy Boiko serhiy.boiko@plvision.eu

[SerhiyBoikoPLV]

We should add a little bit of information (comments) about why we are changing the minimum links to zero.

Added a small comment to the code, updated the commit message to make it more descriptive, and updated the PR description. Also updated one of the commits because there was a bug in cleanup_ip_addrs.

[taraschornyiplv]

@taskin0003 Can you please review?