issue: https://github.com/milvus-io/milvus/issues/41690
- Merge leader view and channel management into ChannelDistManager,
allowing a channel to have multiple delegators.
- Improve shard leader switching to ensure a single replica only has one
shard leader per channel. The shard leader handles all resource loading
and query requests.
- Refine the serviceable mechanism: after QC completes loading, sync the
query view to the delegator. The delegator then determines its
serviceable status based on the query view.
- When a delegator encounters forwarding query or deletion failures,
mark the corresponding segment as offline and transition it to an
unserviceable state.
Signed-off-by: Wei Liu <wei.liu@zilliz.com>
