config+sqldb: make native SQL query config options configurable

Here, we make the sql query option params (batch size and pagination
size) configurable. The defaults for SQLite vs Postgres are still the
same but will be changed in an upcoming commit.

config_test_native_sql.go

@@ -10,6 +10,7 @@ import (
 	"github.com/btcsuite/btcd/chaincfg/chainhash"
 	graphdb "github.com/lightningnetwork/lnd/graph/db"
 	"github.com/lightningnetwork/lnd/kvdb"
+	"github.com/lightningnetwork/lnd/lncfg"
 	"github.com/lightningnetwork/lnd/sqldb"
 	"github.com/lightningnetwork/lnd/sqldb/sqlc"
 )
@@ -30,10 +31,15 @@ func (d *DefaultDatabaseBuilder) getGraphStore(baseDB *sqldb.BaseDB,
 		},
 	)
 
+	queryConfig := d.cfg.DB.Sqlite.QueryConfig
+	if d.cfg.DB.Backend == lncfg.PostgresBackend {
+		queryConfig = d.cfg.DB.Postgres.QueryConfig
+	}
+
 	return graphdb.NewSQLStore(
 		&graphdb.SQLStoreConfig{
 			ChainHash: *d.cfg.ActiveNetParams.GenesisHash,
-			QueryCfg:  sqldb.DefaultQueryConfig(),
+			QueryCfg:  &queryConfig,
 		},
 		graphExecutor, opts...,
 	)