Delete old duckdb index files

default/test/index.duckdb

@@ -1,3 +0,0 @@
-version https://git-lfs.github.com/spec/v1
-oid sha256:54ed022707d058e93e22457335d02a0108f6296a728d28d4308ff83f4047d75a
-size 25702400

default/train/index.duckdb

@@ -1,3 +0,0 @@
-version https://git-lfs.github.com/spec/v1
-oid sha256:1f8465875b60fe3639a7c5ebf5bde42189ab00947886148e4fb9c0b71c139c20
-size 126889984

default/validation/index.duckdb

@@ -1,3 +0,0 @@
-version https://git-lfs.github.com/spec/v1
-oid sha256:1bdfa6a89a46e007267783cb0075384390406c312c5b238b9144732efaf25d08
-size 24391680