Related to #44761
Refactor proxy shard client management by creating a new
internal/proxy/shardclient package. This improves code organization and
modularity by:
- Moving load balancing logic (LookAsideBalancer, RoundRobinBalancer) to
shardclient package
- Extracting shard client manager and related interfaces into separate
package
- Relocating shard leader management and client lifecycle code
- Adding package documentation (README.md, OWNERS)
- Updating proxy code to use the new shardclient package interfaces
This change makes the shard client functionality more maintainable and
better encapsulated, reducing coupling in the proxy layer.
Signed-off-by: Congqi Xia <congqi.xia@zilliz.com>
