1. 10 seconds is an unfortunate pick because that reintroduces the
problem described in commit 5307bf64 (for an earlier check).
Change the +tries=3 +timeout=10 to +tries=2 +time=15, so that we
minimize the risk of dig missing any responses sent by the server in
the first 15 seconds while also increasing our chances of the
response arriving in time on machines under heavy load and allowing
it a single retry in case things go awry.
2. The comment about TCP above was misleading: as painfully proven by
GitLab CI, using TCP is no guarantee of receiving a response in a
timely manner. It may help a bit, but it is certainly not a 100%
reliable solution.
Change the dig invocation to just use UDP like in the two prior
tests for consistency (and revise that comment accordingly).
d3b975abb6