[jdbc-v2] Set default ports, parse multiple endpoints

[enqueue]

Summary

Default port

Client endpoint URLs need to have a port set (see Client). The JdbcConfiguration will use the default ports depending on ssl parameter / http(s) prefix.

Multiple endpoints in JDBC URL

I know that only one endpoint will currently be used, and there is an ongoing discussion in #1870 whether we want to make it the driver's responsibility to maintain liveness states, distribute calls, keep a pool of connections etc. But the current documentation explains that it is possible to give multiple endpoints. Without this PR this would lead to broken connection. With this PR it is more likely that a successful connection can be established. Alternatively "fix" documentation and throw SQLException right away when we detect multiple endpoints in JDBC URL. This would make everything easier 😄 . See #2489 which is an alternative to this PR.

Checklist

• [ ✅ ] Unit and integration tests covering the common scenarios were added

[enqueue]

This is not needed, since multiple endpoints should not be supported via JDBC URL.