Delete old duckdb index files

default/test/index.duckdb

@@ -1,3 +0,0 @@
-version https://git-lfs.github.com/spec/v1
-oid sha256:12244f96c1b62ffa9620ab88a964c83eca2809cd385d4b9569972d4d9d8ae2fa
-size 1060864

default/train/index.duckdb

@@ -1,3 +0,0 @@
-version https://git-lfs.github.com/spec/v1
-oid sha256:f77dae7fc6a7bab9de86efe601c478ac186b8e14e98b61542840cc2f8856687b
-size 1323008

default/validation/index.duckdb

@@ -1,3 +0,0 @@
-version https://git-lfs.github.com/spec/v1
-oid sha256:acd6b7da5a571140dbcf9a8c0e0225f31890a52e6a2d31ec0a1e417cdae4e9a5
-size 1060864