Delete old duckdb index files

dichotomized/test/index.duckdb

@@ -1,3 +0,0 @@
-version https://git-lfs.github.com/spec/v1
-oid sha256:15c41c202bcacd807df2b9ebf68ebc37465cc5637f54a6bcb5d69327f285334d
-size 1585152

dichotomized/train/index.duckdb

@@ -1,3 +0,0 @@
-version https://git-lfs.github.com/spec/v1
-oid sha256:526ac8c68dfc75fc8a301f77fe96e7213d83428c5115240ee28e548c749d5bd9
-size 7352320

dichotomized/validation/index.duckdb

@@ -1,3 +0,0 @@
-version https://git-lfs.github.com/spec/v1
-oid sha256:e84b767f1b4999408b0267010a22639c85e2f3644d3bcb6842a0249f4bf60bed
-size 2109440