The URL blocker checks for resolvable addresses of the URLs it receives.

In some cases, bad/stale URLs do not resolve in a finite time, and lead
to a hang of the call for over the rack/puma timeout levels.

The `Addrinfo.getaddrinfo` call supports passing a timeout since
Ruby 2.7.0, and this change applies a 15 seconds
timeout to the operation.

Fix DNS mock helpers

The existing DNS mock helpers do not support receiving just the timeout
keyword option passed to the getaddrinfo call, leading to the fixture
failures in the pipeline tests.

Fix misunderstanding of DNS helpers

It looks like the merge request
https://gitlab.com/gitlab-org/gitlab/-/merge_requests/40490 had already
added coverage for sending keyword arguments to the getaddrinfo call,
but only in one stub situation

This change attempts to add the same type of mock to the others

Still unsure if this is entirely right for the tests, but will iterate
over if it fails again

Add a test forcing DNS timeout

Attempts adding a test to lower the timeout to unreasonable levels
and expect a DNS lookup failure to occur.

This test may not work as expected on platforms other than Linux due
to its reliance on the `getaddrinfo_a` call existing.

Also fixed are the DNS helpers (yet again) to only look for the
timeout params

Stub new parameter `timeout` also in StubRequests spec helper

Fix failing URL blocker timeout specs

Make DNS stubbing less brittle to changes

Skip timeout specs if it's not available

For example, on OSX getaddrinfo_a is not available.