Delete old duckdb index files

default/train/index.duckdb

@@ -1,3 +0,0 @@
-version https://git-lfs.github.com/spec/v1
-oid sha256:5a833bca380e8de3d9d784a270e4684a6df119c3f7568186a008b7974bfca84e
-size 1323008

whu9--ag_newskeywords_lem/train/index.duckdb

@@ -1,3 +0,0 @@
-version https://git-lfs.github.com/spec/v1
-oid sha256:4d59b9b46eb84d4bac6316e9a707b57b2f9cb708139f38d32d9854607bd42ebc
-size 1323008