chore: Remove version from schema docstrings

[aiven-anton]

Please see separate commits, second one has the schema re-generation.

This addresses a regret. While it's nice to have the full link to the upstream source easily available, this just causes an unjustified amount of churn when rebuilding the schema for a new upstream version. I plan to rebuild the schema for upstream version 3.7 soon, and I want to get this merged beforehand. Being able to see exactly which APIs that changes during a schema update will be more valuable then having the convenience of the link.