Add downstream e2e coverage for LGW L2 as we have for other topologies.

A detail worth noting is that there is a single test case for VRF-Lite that has a long timeout (30) since all the checks need to be done serially as they share infra resources. Adding L2 to the test matrix will likely require a higher timeout. These can have one of two consequences:

• we are required to move the tests to the serial job, which undergoes very careful inspection for alternatives since serial tests are to be kept at a minimum
• we increase the timeout of the existing test which is a tag on the test name. By doing so, we additionally need to migrate the old test name to the new test name on a separate repo to retain history