KAFKA-17058; Extend CoordinatorRuntime to support non-atomic writes

[dajac]

The group coordinator has (internal) write operations that could generate a large number of records (e.g. expiring offsets and groups). At the moment, those operations are limited by the maximum message size. If they hit it, they are basically stuck forever. This patch extends the CoordinatorRuntime to support non-atomic writes and it changes those internal operations to be non-atomic.

Committer Checklist (excluded from commit message)

• [ ] Verify design and implementation
• [ ] Verify test coverage and CI build status
• [ ] Verify documentation (including upgrade notes)