- Removed `pluginDelegateRoundRobin` and related logic to streamline plugin scheduler management.
- Consolidated scheduler strategies under `builtinSchedulerStrategy` with `pickViaBuiltinScheduler`.
- Introduced new methods `pickSingleWithStrategy` and `pickMixedWithStrategy` for strategy-specific behavior.
- Updated tests to reflect changes, including added coverage for round-robin and mixed-provider scenarios.
- Improved maintainability by unifying scheduling logic and reducing redundant structures.