Delete old duckdb index files

default/test/index.duckdb

@@ -1,3 +0,0 @@
-version https://git-lfs.github.com/spec/v1
-oid sha256:b214e93cb3b1989488d71055eaae9e4e5f51b7c2dffb54cc6a9375e66351921e
-size 1323008

default/train/index.duckdb

@@ -1,3 +0,0 @@
-version https://git-lfs.github.com/spec/v1
-oid sha256:3cee85d2515cc5b32d6a09cc8451260ef7309ab2f1256af9e93ae0d8a9c0ca5b
-size 3682304

default/validation/index.duckdb

@@ -1,3 +0,0 @@
-version https://git-lfs.github.com/spec/v1
-oid sha256:bb68c1b2c40ce2b627d40203203f5c27b4bc541b16f221c9186d66a1af2d5489
-size 1323008