Delete old duckdb index files

default/test/index.duckdb

@@ -1,3 +0,0 @@
-version https://git-lfs.github.com/spec/v1
-oid sha256:d29313a1c0c3d5fc112461d15f5403e61d88da16088e787896c75f3b46502920
-size 13643776

default/train/index.duckdb

@@ -1,3 +0,0 @@
-version https://git-lfs.github.com/spec/v1
-oid sha256:9f67906465f34b3bb149456eda2314e9e8723e616f938f7b45e7e32db7152349
-size 97267712

default/validation/index.duckdb

@@ -1,3 +0,0 @@
-version https://git-lfs.github.com/spec/v1
-oid sha256:a9e0de78d8cc22ed1e910d9ad85363f50b966517c814fa2fc50dd5f94ee5e2f7
-size 13381632