issue: #44156
Enhance FlushAll functionality to support targeting specific collections
within databases instead of only database-level flushing.
Changes include:
- Add FlushAllTarget message in data_coord.proto for granular targeting
- Support collection-specific flush operations within databases
- Maintain backward compatibility with deprecated db_name field
This enhancement allows users to flush specific collections without
affecting other collections in the same database, providing more precise
control over data persistence operations.
Signed-off-by: Wei Liu <wei.liu@zilliz.com>
92d2fb6360