Delete old duckdb index files

pclue/test/index.duckdb

@@ -1,3 +0,0 @@
-version https://git-lfs.github.com/spec/v1
-oid sha256:b342ce3124412f9303585d4e5ae86ed3bc3edb78d1d405acbc68bb57a4460d4c
-size 2371584

pclue/train/index.duckdb

@@ -1,3 +0,0 @@
-version https://git-lfs.github.com/spec/v1
-oid sha256:a8b6189c415d08d939bf654ca2ca20cf0f4a18f3c5675160b0d679fe48a59430
-size 647507968

pclue/validation/index.duckdb

@@ -1,3 +0,0 @@
-version https://git-lfs.github.com/spec/v1
-oid sha256:79c533c1992e7de2611da2d54544bff918d74cfa0384768f1d8571dcb531e075
-size 3420160