I've been seeing this more and more as well. More concerning, it seems to be appearing in search results on Google itself, in sort of a self-referential paradox (the links, of course, lead to a 502). Searching for more information led me here, and to images of a "spaceship" on Google Earth and snarky comments about Alphabet.
I'm genuinely curious. Here's hoping more information appears! Honestly it could be a new crawler or something similar still in beta, which would explain "testservice" in the URL, no information readily accessible, and it being hosted on the googleapis domain.