tests: fix wireguard test case failures

tests: fix wireguard test case failures

Type: test

There are random failures in the wireguard test cases that are not related to concurrency issues.
The root cause is a retry of the handshake initiation after (REKEY_TIMEOUT + JITTER) ms, where JITTER is a random value between 0 and 333 ms.

Solution: Add a filter parameter for the `send_and_expect` method of the vpptestcase.
This filter allows for excluding unexpected handshake initiation packets when the responder sends two packets (with `message_type = 1` and `message_type = 2`),while only a single packet (with `message_type = 2`) is expected.

Change-Id: I62816931fc1b85e2202f3d36eb6c2a23714644d5
Signed-off-by: Ivan Ivanets <[email protected]>