Silence long-term one-hop circuit diagnostic for single onion intro point circuits
In legacy/trac#8387 (moved), we track long-term single-hop circuits.
But single onion services deliberately open long-term, one-hop introduction point circuits: https://trac.torproject.org/projects/tor/ticket/8387?replyto=50#comment:50
So we should silence this message for single onion service intro point circuits.