Remove SNI test that trigger request to sni.velox.ch

This has been requested by Kaspar Brand who provides
sni.velox.ch. That site is only for interactive
testing and not for unit/integration/regression testing.
Although this test is run only in special cases (when
SNI_TESTS is defined) it should still be removed.

Also this test is not reliable as it depends on external
resources.

Author: bukka