test: Ignore tcp-connect-timeout on freebsd

The BSD builders are failing with a different error that is not a timeout error
(Connection reset by peer), so this test isn't really all that useful on
freebsd. Due to a lack of a better idea of how to test a connect timeout, this
test is going to just be ignored for now.
auto merge of #13689 : alexcrichton/rust/ignore-tcp-connect-freebsd, r=brson

The BSD builders are failing with a different error that is not a timeout error
(Connection reset by peer), so this test isn't really all that useful on
freebsd. Due to a lack of a better idea of how to test a connect timeout, this
test is going to just be ignored for now.