[Docs] Remove of savepoints from Java, Ruby, and Node driver/ORM documentation

[jseldess]

Background: https://airtable.com/tblD3oZPLJgGhCmch/viw1DKmbKhg2MIECH/recziV8w8VyG54oRz

Description: CockroachDB docs examples now do not mention savepoints in their retry logic examples.

We recommend the use of Savepoints as part of the retry logic needed to address transaction retries. This is unnecessarily confusing for application developers at it offers little benefit beyond simple application retry logic.

Team: Andrew Woods, Rafi Shamim, Richard Loveland

Github Tracking Issue: #5035

[jseldess]

Closing in favor of #5035