Update store tests to cover data column pruning

[jimmygchen]

Description

There are a few TODOs in store_tests.rs to add tests to cover data column pruning that needs to be addressed:

lighthouse/beacon_node/beacon_chain/tests/store_tests.rs

Lines 3078 to 3080 in 98863da

	if store.get_chain_spec().is_peer_das_scheduled() {
	// TODO(fulu): add prune tests for Fulu / PeerDAS data columns.
	return;