test: handle SmartOS bug in test-tls-session-cache

Sometimes, a SmartOS bug results in ECONNREFUSED when trying to connect
to the TLS server that the test starts. Retry in that situation.

Fixes: https://github.com/nodejs/node/issues/5111
Refs: https://smartos.org/bugview/OS-2767
PR-URL: https://github.com/nodejs/node/pull/7505


Reviewed-By: Santiago Gimeno <santiago.gimeno@gmail.com>