vxlan: add l2 mode test
vxlan: add l2 mode test

The same test for v22.02 was already merged: https://gerrit.fd.io/r/c/vpp/+/35390

Type: improvement

Signed-off-by: Artem Glazychev <441b52f84e057ab1215b5caeaea1cdeb3a6be2f5@xored.com>
Change-Id: I214f6fb5b63d97ca4afe3b10fd2d3e3410b5a6e4

chrisy/vpp,FDio/vpp,FDio/vpp,FDio/vpp,chrisy/vpp,chrisy/vpp,chrisy/vpp,FDio/vpp,FDio/vpp,chrisy/vpp,FDio/vpp,FDio/vpp,chrisy/vpp,FDio/vpp,chrisy/vpp,chrisy/vpp