[TC] [Connstr] An omitted port should be -1 instead of 0

What's the issue?
The valid port range is 1-65535 (where 1-1023 are reserved), we currently use a zero value to indicate that the port hasn't been supplied by a user (in the connection string).

While this doesn't haven't any immediate negative impact on connection string parsing/use, it is incorrect because zero use often used by OSs for special functionality (e.g. pick and unused port).

What's the fix?
We should use -1 instead of 0 for a port that wasn't provided by the user.