remove split_slot

Author: chong-he

beacon_node/beacon_chain/tests/store_tests.rs

@@ -3571,7 +3571,6 @@ fn check_split_slot(
 /// Check that all the states in a chain dump have the correct tree hash.
 fn check_chain_dump(harness: &TestHarness, expected_len: u64) {
     let mut chain_dump = harness.chain.chain_dump().unwrap();
-    let split_slot = harness.chain.store.get_split_slot();
 
     assert_eq!(chain_dump.len() as u64, expected_len);