Delete old duckdb index files

test/train/index.duckdb

@@ -1,3 +0,0 @@
-version https://git-lfs.github.com/spec/v1
-oid sha256:f22acaf4fbcaa76b5c21411ba471afb78fae0fc1183fe5feba4463595499b214
-size 107229184

train/train/index.duckdb

@@ -1,3 +0,0 @@
-version https://git-lfs.github.com/spec/v1
-oid sha256:a1a4344b769e6f2ab0657102c88aedd09e32555aab747dde40d949710839de1c
-size 721432576

validation/train/index.duckdb

@@ -1,3 +0,0 @@
-version https://git-lfs.github.com/spec/v1
-oid sha256:29017f1d1f584e5b8cc575e24e68250a3f963f90c9d7b083abe426db80900c73
-size 64761856