issue: #43858
Refactor the balance checker implementation to use priority queues for
managing collection balance operations, improving processing efficiency
and order control.
Changes include:
- Export priority queue interfaces (Item, BaseItem, PriorityQueue)
- Replace collection round-robin with priority-based queue system
- Add BalanceCheckCollectionMaxCount configuration parameter
- Optimize balance task generation with batch processing limits
- Refactor processBalanceQueue method for different strategies
- Enhance test coverage with comprehensive unit tests
The new priority queue system processes collections based on row count
or collection ID order, providing better control over balance operation
priorities and resource utilization.
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Signed-off-by: Wei Liu <wei.liu@zilliz.com>
