internal/postgres: use a more straightforward return value

Change-Id: I954ebf3d4908839e7c7e746b142127887fd936c5
Reviewed-on: https://go-review.googlesource.com/c/pkgsite/+/653216
Auto-Submit: Carlos Amedee <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>
Reviewed-by: Robert Findley <[email protected]>
kokoro-CI: kokoro <[email protected]>
Reviewed-by: Carlos Amedee <[email protected]>

Author: cuishuang

Diff for: internal/postgres/delete_test.go

@@ -134,7 +134,7 @@ func readSearchDocuments(ctx context.Context, db *DB) ([]searchDocumentRow, erro
 	if err != nil {
 		return nil, err
 	}
-	return rows, err
+	return rows, nil
 }
 
 func checkSearchDocuments(ctx context.Context, t *testing.T, db *DB, want []searchDocumentRow) {