etcd+channeldb: fix linter issues, rename receiver

With this commit we address some issues the linter picked up after
touching older code.

kvdb/etcd/db_test.go

@@ -38,7 +38,7 @@ func TestCopy(t *testing.T) {
 	require.Nil(t, err)
 
 	expected := map[string]string{
-		BucketKey("apple"):        BucketVal("apple"),
+		BucketKey("apple"):       BucketVal("apple"),
 		ValueKey("key", "apple"): "val",
 	}
 	require.Equal(t, expected, f.Dump())

kvdb/etcd/fixture.go

@@ -11,7 +11,7 @@ import (
 
 	"github.com/btcsuite/btcwallet/walletdb"
 	"github.com/stretchr/testify/require"
-	"go.etcd.io/etcd/client/v3"
+	clientv3 "go.etcd.io/etcd/client/v3"
 	"go.etcd.io/etcd/client/v3/namespace"
 )
 

kvdb/etcd/readwrite_tx_test.go

@@ -85,7 +85,7 @@ func TestChangeDuringUpdate(t *testing.T) {
 	require.Equal(t, count, 2)
 
 	expected := map[string]string{
-		BucketKey("apple"):         BucketVal("apple"),
+		BucketKey("apple"):        BucketVal("apple"),
 		ValueKey("key", "apple"):  "value",
 		ValueKey("key2", "apple"): "value2",
 	}