Fix snowflake ssh tunnel (#39283) (#39465)

* Fix snowflake ssh tunnel

* Put test where it will run in CI

* Override incorporate-ssh-tunnel

* Revert snowflake in util.ssh-test

* Move tunnel connection tests to sql_jdbc

* Add mock-server fixture

* Exclude drivers from tunnel test

* Fix up reconnection tests

* Exclude more drivers

* Address PR feedback

Co-authored-by: Case Nelson <case@metabase.com>