is not indexed.

btr_search_update_hash_ref(), btr_search_drop_page_hash_index(),
btr_search_build_page_hash_index(), btr_search_update_hash_on_delete(),
btr_search_update_hash_node_on_insert(), btr_search_update_hash_on_insert(),
btr_search_validate():
Assert that hashed blocks do not belong to the insert buffer tree.

btr_search_move_or_delete_hash_entries():
When invoked on the insert buffer tree, assert that neither block is hashed.