TUN-10383: Set edge-ip-version to auto

To allow pre-checks to test both IPv6 and IPv4, we must change the default value of edge-ip-version's from 4 to auto. This will allows the tunnel (and pre-check) to probe both IPv4 and IPv6 addresses by default, respecting the system's DNS preference. Instead of always preferring IPv4, cloudflared will now use whichever address family the system resolver returns first.