Pair nodes dynamically via a distributed coordination backend for
network burn-in. The algorithm uses a group to pair nodes: after
acquiring a lock, a first node joins the group, releases the lock,
waits for a second node, then they both leave, and release the lock
for the next pair.
Story: #2007523
Task: #42796
Change-Id: I572093b144bc90a49cd76929c7e8685ed45d9f6e