Distinguish TLS connections in connectioncounter
The connectioncounter prometheus metric tells us how many network connections Gitaly is accepting. It has a label type
indicating if the connection is on a Unix socket or a regular TCP connection.
Before this change, TLS connections got lumped in with TCP connections. After this change TLS connections should be counted separately. This helps when rolling out TLS because you can see if any old clients are still making non-TLS connections to Gitaly.