registry: add tests for unresolvable domain names in isSecure

Signed-off-by: Tibor Vass <teabee89@gmail.com>
registry: handle unresolvable domain names in isSecure
to allow HTTP proxies to work as expected.

Fixes #9708

Signed-off-by: Tibor Vass <teabee89@gmail.com>
Merge pull request #9735 from tiborvass/fix-issecure-for-http-proxies

Handle unresolvable domain names in isSecure to allow HTTP proxies to work as expected