Fallback should optimistically pick a new hostname when it falls back

[connor4312]

          @roblourens it is working kind of, when I add the host entry ::1 to the host file.

$ ping localhost
PING localhost(ipv6-localhost (::1)) 56 data bytes
64 bytes from ipv6-localhost (::1): icmp_seq=1 ttl=64 time=0.024 ms

However when I refresh or hard-refresh sometimes the breakpoints don't get it, and sometime it will get it. Also I've noticed things run much slower now to the point I wouldn't want to use this debugger.

So to check, I commented out host entry ::1 in my hosts file and the debugger works all the time and it really responsive. When I do a refresh the breakpoint gets hit instantly.

$ ping localhost
PING localhost (127.0.0.1) 56(84) bytes of data.
64 bytes from localhost (127.0.0.1): icmp_seq=1 ttl=64 time=0.162 ms

Originally posted by @rajinder-yadav in microsoft/vscode#167353 (comment)

[connor4312]

@rajinder-yadav you should see better performance in the forthcoming nightly build