[2.4]: enhance alterIndex (milvus-io#368)

Signed-off-by: Xianhui.Lin <[email protected]>

Author: JsDove

proto/milvus.proto

@@ -28,7 +28,6 @@ service MilvusService {
   rpc ShowCollections(ShowCollectionsRequest) returns (ShowCollectionsResponse) {}
   rpc AlterCollection(AlterCollectionRequest) returns (common.Status) {}
   rpc AlterCollectionField(AlterCollectionFieldRequest) returns (common.Status) {}
-
   rpc CreatePartition(CreatePartitionRequest) returns (common.Status) {}
   rpc DropPartition(DropPartitionRequest) returns (common.Status) {}
   rpc HasPartition(HasPartitionRequest) returns (BoolResponse) {}