Delete old duckdb index files

default/train/index.duckdb

@@ -1,3 +0,0 @@
-version https://git-lfs.github.com/spec/v1
-oid sha256:8a118442ac1e42716a2ea09e40f41809681a38897b5dc7d319e1f46f964f6893
-size 152317952

default/validation/index.duckdb

@@ -1,3 +0,0 @@
-version https://git-lfs.github.com/spec/v1
-oid sha256:7a72eeb639da8d878e999961dbc052e2e7ebd3a6e33ceebbae4f8a26d8e3a6ad
-size 18100224