store/driver: update unionstore import path (pingcap#25823)

store/driver/txn/unionstore_driver.go

@@ -19,15 +19,15 @@ import (
 	"github.com/pingcap/tidb/kv"
 	derr "github.com/pingcap/tidb/store/driver/error"
 	tikvstore "github.com/tikv/client-go/v2/kv"
-	"github.com/tikv/client-go/v2/unionstore"
+	"github.com/tikv/client-go/v2/tikv"
 )
 
-// memBuffer wraps unionstore.MemDB as kv.MemBuffer.
+// memBuffer wraps tikv.MemDB as kv.MemBuffer.
 type memBuffer struct {
-	*unionstore.MemDB
+	*tikv.MemDB
 }
 
-func newMemBuffer(m *unionstore.MemDB) kv.MemBuffer {
+func newMemBuffer(m *tikv.MemDB) kv.MemBuffer {
 	if m == nil {
 		return nil
 	}
@@ -112,10 +112,10 @@ func (m *memBuffer) SnapshotGetter() kv.Getter {
 }
 
 type tikvGetter struct {
-	unionstore.Getter
+	tikv.Getter
 }
 
-func newKVGetter(getter unionstore.Getter) kv.Getter {
+func newKVGetter(getter tikv.Getter) kv.Getter {
 	return &tikvGetter{Getter: getter}
 }
 
@@ -124,12 +124,12 @@ func (g *tikvGetter) Get(_ context.Context, k kv.Key) ([]byte, error) {
 	return data, derr.ToTiDBErr(err)
 }
 
-// tikvIterator wraps unionstore.Iterator as kv.Iterator
+// tikvIterator wraps tikv.Iterator as kv.Iterator
 type tikvIterator struct {
-	unionstore.Iterator
+	tikv.Iterator
 }
 
-func newKVIterator(it unionstore.Iterator) kv.Iterator {
+func newKVIterator(it tikv.Iterator) kv.Iterator {
 	if it == nil {
 		return nil
 	}