Update duckdb index files

.gitattributes

@@ -276,3 +276,4 @@ igbo/test/index.duckdb filter=lfs diff=lfs merge=lfs -text
 igbo/validation/index.duckdb filter=lfs diff=lfs merge=lfs -text
 indonesian/train/index.duckdb filter=lfs diff=lfs merge=lfs -text
 indonesian/test/index.duckdb filter=lfs diff=lfs merge=lfs -text
+japanese/train/index.duckdb filter=lfs diff=lfs merge=lfs -text

japanese/train/index.duckdb

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:779671de742979c9ea382373b5bfbcdbe81c04de2f74e3c04077aafee9e07e7d
+size 28323840