[skip ci] Fix golint error in querynode (#9288)

Signed-off-by: zhenshan.cao <zhenshan.cao@zilliz.com>

internal/querynode/partition.go

@@ -28,12 +28,14 @@ import (
 	"github.com/milvus-io/milvus/internal/log"
 )
 
+// Partition is a logical division of Collection and can be considered as an attribute of Segment.
 type Partition struct {
 	collectionID UniqueID
 	partitionID  UniqueID
 	segmentIDs   []UniqueID
 }
 
+// ID returns the identity of the partition.
 func (p *Partition) ID() UniqueID {
 	return p.partitionID
 }